diff --git a/content/lessons/quant/quant-arithmetic-exponents-roots.md b/content/lessons/quant/quant-arithmetic-exponents-roots.md new file mode 100644 index 0000000..736d01a --- /dev/null +++ b/content/lessons/quant/quant-arithmetic-exponents-roots.md @@ -0,0 +1,79 @@ +--- +id: quant-arithmetic-exponents-roots +section: quant +topic: arithmetic +subtopic: exponents-roots +title: "Exponents & Roots" +tags: [exponents, roots, radicals, powers] +author: openmat +reviewers: [] +status: in-review +original: true +license: CC-BY-SA-4.0 +--- + +## Overview + +Exponents and roots show up all over GMAT Focus Quant — inside number-properties questions, in +disguised equations, and as the fast way to compare very large or very small quantities. Almost +everything reduces to a short list of rules plus one habit: **rewrite every base as a power of the +same prime before you do anything else.** + +## Core concepts + +**The exponent rules.** For any nonzero base and integer (or rational) exponents: + +- Product: \(a^m \cdot a^n = a^{m+n}\) — same base, *add* exponents. +- Quotient: \(\dfrac{a^m}{a^n} = a^{m-n}\) — same base, *subtract* exponents. +- Power of a power: \((a^m)^n = a^{mn}\) — *multiply* exponents. +- Distributes over products: \((ab)^n = a^n b^n\). + +**Zero and negative exponents.** + +\[a^0 = 1 \quad (a \ne 0), \qquad a^{-n} = \frac{1}{a^n}\] + +A negative exponent means "reciprocal," not "negative number." So \(2^{-2} = \tfrac14\), which is +positive. + +**Roots are fractional exponents.** This is the single most useful bridge: + +\[\sqrt[n]{a} = a^{1/n}, \qquad a^{m/n} = \left(\sqrt[n]{a}\right)^m = \sqrt[n]{a^m}\] + +So \(27^{2/3} = \left(27^{1/3}\right)^2 = 3^2 = 9\). Take the root first (smaller numbers), then the power. + +**Simplifying radicals.** Pull perfect-square factors out from under a square root, and combine only +*like* radicals: + +\[\sqrt{ab} = \sqrt{a}\,\sqrt{b}, \qquad \sqrt{50} = \sqrt{25\cdot 2} = 5\sqrt{2}\] + +You can add \(5\sqrt2 + 3\sqrt2 = 8\sqrt2\), but you **cannot** turn \(\sqrt2 + \sqrt2\) into +\(\sqrt4\). + +**Same-base strategy for equations.** When an equation has different bases that are all powers of one +prime, rewrite them and set the exponents equal: + +\[4^{x+1} = 8^{x-1} \;\Rightarrow\; 2^{2(x+1)} = 2^{3(x-1)} \;\Rightarrow\; 2x+2 = 3x-3 \;\Rightarrow\; x = 5\] + +## Worked examples + +**Combine rules.** Simplify \((x^2)^3 \cdot x^4\). Power of a power gives \(x^{6}\); then the product +rule adds exponents: \(x^{6} \cdot x^{4} = x^{10}\). + +**Fractional exponent.** Evaluate \(27^{2/3}\). Cube root of 27 is 3; square it: \(3^2 = 9\). + +**Radicals.** Simplify \(\sqrt{50} + \sqrt{18} = 5\sqrt2 + 3\sqrt2 = 8\sqrt2\). + +## Common traps + +- **Multiplying exponents when you should add.** \(2^5 \cdot 2^3 = 2^{8}\), not \(2^{15}\). You only + multiply exponents for a *power of a power*, \((2^5)^3 = 2^{15}\). +- **Negative exponent → negative number.** \(3^{-1} = \tfrac13\), a positive fraction, not \(-3\). +- **Adding under the radical.** \(\sqrt{a} + \sqrt{b} \ne \sqrt{a+b}\). \(\sqrt{9} + \sqrt{16} = 3+4 = 7\), not \(\sqrt{25} = 5\). +- **Combining unlike bases.** \(2^3 \cdot 3^3\) is \((2\cdot3)^3 = 6^3\), but \(2^3 \cdot 3^2\) cannot be merged into one base. + +## Key takeaways + +- Same base: add exponents to multiply, subtract to divide, multiply to raise a power to a power. +- \(a^0 = 1\) and \(a^{-n} = 1/a^n\); negative exponents give positive reciprocals. +- Roots are fractional exponents: \(a^{m/n} = \sqrt[n]{a^m}\) — take the root first, then the power. +- To solve exponential equations, rewrite every base as the same prime and equate the exponents. diff --git a/content/questions/quant/quant-arithmetic-exponents-roots-0017.md b/content/questions/quant/quant-arithmetic-exponents-roots-0017.md new file mode 100644 index 0000000..c6dc952 --- /dev/null +++ b/content/questions/quant/quant-arithmetic-exponents-roots-0017.md @@ -0,0 +1,42 @@ +--- +id: quant-arithmetic-exponents-roots-0017 +section: quant +topic: arithmetic +subtopic: exponents-roots +type: problem-solving +difficulty: easy +tags: [exponents, quotient-rule] +choices: + A: "5" + B: "25" + C: "125" + D: "625" + E: "5^{11}" +answer: C +author: openmat +reviewers: [] +status: in-review +original: true +license: CC-BY-SA-4.0 +--- + +## Question + +What is the value of \(\dfrac{5^{7}}{5^{4}}\)? + +## Explanation + +Same base, division — **subtract** the exponents: + +\[\frac{5^{7}}{5^{4}} = 5^{7-4} = 5^{3} = 125\] + +The answer is **125**. + +**The traps:** choice **E** (\(5^{11}\)) *adds* the exponents, which is the rule for +*multiplication*, not division. Choices that divide the exponents (\(7 \div 4\)) or cancel bases +incorrectly land on the smaller powers of 5. + +## Hints + +- Same base with division: what do you do to the exponents? +- \(5^{7} / 5^{4} = 5^{7-4}\). Now just evaluate the small power. diff --git a/content/questions/quant/quant-arithmetic-exponents-roots-0018.md b/content/questions/quant/quant-arithmetic-exponents-roots-0018.md new file mode 100644 index 0000000..2cfbbd0 --- /dev/null +++ b/content/questions/quant/quant-arithmetic-exponents-roots-0018.md @@ -0,0 +1,46 @@ +--- +id: quant-arithmetic-exponents-roots-0018 +section: quant +topic: arithmetic +subtopic: exponents-roots +type: problem-solving +difficulty: easy +tags: [exponents, zero-exponent, negative-exponent] +choices: + A: "0" + B: "1" + C: "1.25" + D: "1.5" + E: "9" +answer: C +author: openmat +reviewers: [] +status: in-review +original: true +license: CC-BY-SA-4.0 +--- + +## Question + +What is the value of \(7^{0} + 2^{-2}\)? + +## Explanation + +Handle each term with the definitions of the zero and negative exponents: + +\[7^{0} = 1, \qquad 2^{-2} = \frac{1}{2^{2}} = \frac{1}{4}\] + +So the sum is + +\[1 + \frac{1}{4} = \frac{5}{4} = 1.25\] + +The answer is **1.25**. + +**The traps:** choice **A (0)** assumes \(7^0 = 0\), but any nonzero base to the zero power is 1. +Choice **E (9)** reads \(2^{-2}\) as \(-2\times 2\) or \(2^2\) plus a sign slip — a negative exponent +gives a positive *reciprocal*, not a negative number. + +## Hints + +- Any nonzero number raised to the power 0 equals 1 — not 0. +- A negative exponent means take the reciprocal: \(2^{-2} = 1/2^{2}\), a positive fraction. diff --git a/content/questions/quant/quant-arithmetic-exponents-roots-0019.md b/content/questions/quant/quant-arithmetic-exponents-roots-0019.md new file mode 100644 index 0000000..4677fc8 --- /dev/null +++ b/content/questions/quant/quant-arithmetic-exponents-roots-0019.md @@ -0,0 +1,47 @@ +--- +id: quant-arithmetic-exponents-roots-0019 +section: quant +topic: arithmetic +subtopic: exponents-roots +type: problem-solving +difficulty: medium +tags: [exponents, power-of-a-power, product-rule, variables] +choices: + A: "x^{9}" + B: "x^{10}" + C: "x^{12}" + D: "x^{14}" + E: "x^{24}" +answer: B +author: openmat +reviewers: [] +status: in-review +original: true +license: CC-BY-SA-4.0 +--- + +## Question + +For \(x \neq 0\), which of the following is equal to \(\left(x^{2}\right)^{3} \cdot x^{4}\)? + +## Explanation + +Apply the rules in order. First, **power of a power** — multiply the exponents: + +\[\left(x^{2}\right)^{3} = x^{2\cdot 3} = x^{6}\] + +Then the **product rule** — same base, add the exponents: + +\[x^{6} \cdot x^{4} = x^{6+4} = x^{10}\] + +The answer is **\(x^{10}\)**. + +**The traps:** choice **E** (\(x^{24}\)) multiplies all three exponents (\(2\cdot 3\cdot 4\)) as if +everything were a power of a power. Choice **A** (\(x^{9}\)) adds \(2+3+4\), mixing up which +operation adds and which multiplies. Multiply for a power raised to a power; add when multiplying +like bases. + +## Hints + +- Do the inner operation first: \((x^2)^3\) is a power raised to a power. +- Once you have a single power of \(x\) times another, add those two exponents. diff --git a/content/questions/quant/quant-arithmetic-exponents-roots-0020.md b/content/questions/quant/quant-arithmetic-exponents-roots-0020.md new file mode 100644 index 0000000..d0bc9d3 --- /dev/null +++ b/content/questions/quant/quant-arithmetic-exponents-roots-0020.md @@ -0,0 +1,46 @@ +--- +id: quant-arithmetic-exponents-roots-0020 +section: quant +topic: arithmetic +subtopic: exponents-roots +type: problem-solving +difficulty: medium +tags: [roots, radicals, simplifying-radicals] +choices: + A: "\\sqrt{68}" + B: "2\\sqrt{17}" + C: "8\\sqrt{2}" + D: "15\\sqrt{2}" + E: "34" +answer: C +author: openmat +reviewers: [] +status: in-review +original: true +license: CC-BY-SA-4.0 +--- + +## Question + +What is \(\sqrt{50} + \sqrt{18}\) in simplest form? + +## Explanation + +Pull the perfect-square factor out of each radical, then combine the *like* radicals: + +\[\sqrt{50} = \sqrt{25 \cdot 2} = 5\sqrt{2}, \qquad \sqrt{18} = \sqrt{9 \cdot 2} = 3\sqrt{2}\] + +Both are multiples of \(\sqrt2\), so add the coefficients: + +\[5\sqrt{2} + 3\sqrt{2} = 8\sqrt{2}\] + +The answer is **\(8\sqrt{2}\)**. + +**The traps:** choice **A** (\(\sqrt{68}\)) adds *under* the radical (\(50+18\)), but +\(\sqrt{a} + \sqrt{b} \neq \sqrt{a+b}\). Choice **D** (\(15\sqrt2\)) multiplies the coefficients +instead of adding them. You may add radicals only when the parts under the root already match. + +## Hints + +- Factor out the largest perfect square from each radical first. +- After simplifying, both terms are multiples of \(\sqrt2\). Add only the numbers in front. diff --git a/content/questions/quant/quant-arithmetic-exponents-roots-0021.md b/content/questions/quant/quant-arithmetic-exponents-roots-0021.md new file mode 100644 index 0000000..32f1bf7 --- /dev/null +++ b/content/questions/quant/quant-arithmetic-exponents-roots-0021.md @@ -0,0 +1,43 @@ +--- +id: quant-arithmetic-exponents-roots-0021 +section: quant +topic: arithmetic +subtopic: exponents-roots +type: problem-solving +difficulty: medium +tags: [exponents, fractional-exponents, roots] +choices: + A: "6" + B: "9" + C: "18" + D: "81" + E: "729" +answer: B +author: openmat +reviewers: [] +status: in-review +original: true +license: CC-BY-SA-4.0 +--- + +## Question + +What is the value of \(27^{2/3}\)? + +## Explanation + +A fractional exponent combines a root and a power: the denominator is the root, the numerator is the +power. Take the root **first** to keep the numbers small: + +\[27^{2/3} = \left(27^{1/3}\right)^{2} = \left(\sqrt[3]{27}\right)^{2} = 3^{2} = 9\] + +The answer is **9**. + +**The traps:** choice **E** (\(729 = 27^2\)) ignores the cube root entirely. Choice **C (18)** +multiplies the base by the exponent (\(27 \times \tfrac23\)). Choice **A (6)** takes the cube root +but then multiplies by 2 instead of squaring. + +## Hints + +- Rewrite the exponent as a root and a power: the bottom of the fraction is the root. +- Cube root of 27 is a small number — find it first, then apply the remaining power. diff --git a/content/questions/quant/quant-arithmetic-exponents-roots-0022.md b/content/questions/quant/quant-arithmetic-exponents-roots-0022.md new file mode 100644 index 0000000..03d9e31 --- /dev/null +++ b/content/questions/quant/quant-arithmetic-exponents-roots-0022.md @@ -0,0 +1,49 @@ +--- +id: quant-arithmetic-exponents-roots-0022 +section: quant +topic: arithmetic +subtopic: exponents-roots +type: problem-solving +difficulty: hard +tags: [exponents, exponential-equations, same-base] +choices: + A: "2" + B: "3" + C: "4" + D: "5" + E: "7" +answer: D +author: openmat +reviewers: [] +status: in-review +original: true +license: CC-BY-SA-4.0 +--- + +## Question + +If \(4^{x+1} = 8^{x-1}\), what is the value of \(x\)? + +## Explanation + +The bases 4 and 8 are both powers of 2, so rewrite everything with base 2: + +\[4^{x+1} = \left(2^{2}\right)^{x+1} = 2^{2(x+1)}, \qquad 8^{x-1} = \left(2^{3}\right)^{x-1} = 2^{3(x-1)}\] + +With a common base, the exponents must be equal: + +\[2(x+1) = 3(x-1)\] +\[2x + 2 = 3x - 3\] +\[x = 5\] + +The answer is **5**. + +**Check:** \(4^{6} = 4096\) and \(8^{4} = 4096\). ✓ + +**The trap:** trying to compare 4 and 8 directly, or guessing a small value, misses the key move — +express both sides as powers of the same prime, then set the exponents equal. + +## Hints + +- Both 4 and 8 are powers of 2. Rewrite each side with base 2. +- Once the bases match, the exponents must be equal — solve the resulting linear equation. diff --git a/docs/data/content.json b/docs/data/content.json index 9ef981c..c53a749 100644 --- a/docs/data/content.json +++ b/docs/data/content.json @@ -7,8 +7,8 @@ "stats": { "quant": { "label": "Quantitative", - "questions": 16, - "lessons": 5 + "questions": 22, + "lessons": 6 }, "verbal": { "label": "Verbal", @@ -22,8 +22,8 @@ } }, "counts": { - "questions": 32, - "lessons": 8 + "questions": 38, + "lessons": 9 }, "questions": [ { @@ -301,6 +301,186 @@ "Or use the coefficient shortcut: sum of roots \\(= -b\\), product \\(= c\\)." ] }, + { + "id": "quant-arithmetic-exponents-roots-0017", + "section": "quant", + "topic": "arithmetic", + "subtopic": "exponents-roots", + "type": "problem-solving", + "difficulty": "easy", + "tags": [ + "exponents", + "quotient-rule" + ], + "choices": { + "A": "5", + "B": "25", + "C": "125", + "D": "625", + "E": "5^{11}" + }, + "answer": "C", + "author": "openmat", + "reviewers": [], + "status": "in-review", + "prompt": "What is the value of \\(\\dfrac{5^{7}}{5^{4}}\\)?", + "explanation": "Same base, division — **subtract** the exponents:\n\n\\[\\frac{5^{7}}{5^{4}} = 5^{7-4} = 5^{3} = 125\\]\n\nThe answer is **125**.\n\n**The traps:** choice **E** (\\(5^{11}\\)) *adds* the exponents, which is the rule for\n*multiplication*, not division. Choices that divide the exponents (\\(7 \\div 4\\)) or cancel bases\nincorrectly land on the smaller powers of 5.", + "hints": [ + "Same base with division: what do you do to the exponents?", + "\\(5^{7} / 5^{4} = 5^{7-4}\\). Now just evaluate the small power." + ] + }, + { + "id": "quant-arithmetic-exponents-roots-0018", + "section": "quant", + "topic": "arithmetic", + "subtopic": "exponents-roots", + "type": "problem-solving", + "difficulty": "easy", + "tags": [ + "exponents", + "zero-exponent", + "negative-exponent" + ], + "choices": { + "A": "0", + "B": "1", + "C": "1.25", + "D": "1.5", + "E": "9" + }, + "answer": "C", + "author": "openmat", + "reviewers": [], + "status": "in-review", + "prompt": "What is the value of \\(7^{0} + 2^{-2}\\)?", + "explanation": "Handle each term with the definitions of the zero and negative exponents:\n\n\\[7^{0} = 1, \\qquad 2^{-2} = \\frac{1}{2^{2}} = \\frac{1}{4}\\]\n\nSo the sum is\n\n\\[1 + \\frac{1}{4} = \\frac{5}{4} = 1.25\\]\n\nThe answer is **1.25**.\n\n**The traps:** choice **A (0)** assumes \\(7^0 = 0\\), but any nonzero base to the zero power is 1.\nChoice **E (9)** reads \\(2^{-2}\\) as \\(-2\\times 2\\) or \\(2^2\\) plus a sign slip — a negative exponent\ngives a positive *reciprocal*, not a negative number.", + "hints": [ + "Any nonzero number raised to the power 0 equals 1 — not 0.", + "A negative exponent means take the reciprocal: \\(2^{-2} = 1/2^{2}\\), a positive fraction." + ] + }, + { + "id": "quant-arithmetic-exponents-roots-0019", + "section": "quant", + "topic": "arithmetic", + "subtopic": "exponents-roots", + "type": "problem-solving", + "difficulty": "medium", + "tags": [ + "exponents", + "power-of-a-power", + "product-rule", + "variables" + ], + "choices": { + "A": "x^{9}", + "B": "x^{10}", + "C": "x^{12}", + "D": "x^{14}", + "E": "x^{24}" + }, + "answer": "B", + "author": "openmat", + "reviewers": [], + "status": "in-review", + "prompt": "For \\(x \\neq 0\\), which of the following is equal to \\(\\left(x^{2}\\right)^{3} \\cdot x^{4}\\)?", + "explanation": "Apply the rules in order. First, **power of a power** — multiply the exponents:\n\n\\[\\left(x^{2}\\right)^{3} = x^{2\\cdot 3} = x^{6}\\]\n\nThen the **product rule** — same base, add the exponents:\n\n\\[x^{6} \\cdot x^{4} = x^{6+4} = x^{10}\\]\n\nThe answer is **\\(x^{10}\\)**.\n\n**The traps:** choice **E** (\\(x^{24}\\)) multiplies all three exponents (\\(2\\cdot 3\\cdot 4\\)) as if\neverything were a power of a power. Choice **A** (\\(x^{9}\\)) adds \\(2+3+4\\), mixing up which\noperation adds and which multiplies. Multiply for a power raised to a power; add when multiplying\nlike bases.", + "hints": [ + "Do the inner operation first: \\((x^2)^3\\) is a power raised to a power.", + "Once you have a single power of \\(x\\) times another, add those two exponents." + ] + }, + { + "id": "quant-arithmetic-exponents-roots-0020", + "section": "quant", + "topic": "arithmetic", + "subtopic": "exponents-roots", + "type": "problem-solving", + "difficulty": "medium", + "tags": [ + "roots", + "radicals", + "simplifying-radicals" + ], + "choices": { + "A": "\\\\sqrt{68}", + "B": "2\\\\sqrt{17}", + "C": "8\\\\sqrt{2}", + "D": "15\\\\sqrt{2}", + "E": "34" + }, + "answer": "C", + "author": "openmat", + "reviewers": [], + "status": "in-review", + "prompt": "What is \\(\\sqrt{50} + \\sqrt{18}\\) in simplest form?", + "explanation": "Pull the perfect-square factor out of each radical, then combine the *like* radicals:\n\n\\[\\sqrt{50} = \\sqrt{25 \\cdot 2} = 5\\sqrt{2}, \\qquad \\sqrt{18} = \\sqrt{9 \\cdot 2} = 3\\sqrt{2}\\]\n\nBoth are multiples of \\(\\sqrt2\\), so add the coefficients:\n\n\\[5\\sqrt{2} + 3\\sqrt{2} = 8\\sqrt{2}\\]\n\nThe answer is **\\(8\\sqrt{2}\\)**.\n\n**The traps:** choice **A** (\\(\\sqrt{68}\\)) adds *under* the radical (\\(50+18\\)), but\n\\(\\sqrt{a} + \\sqrt{b} \\neq \\sqrt{a+b}\\). Choice **D** (\\(15\\sqrt2\\)) multiplies the coefficients\ninstead of adding them. You may add radicals only when the parts under the root already match.", + "hints": [ + "Factor out the largest perfect square from each radical first.", + "After simplifying, both terms are multiples of \\(\\sqrt2\\). Add only the numbers in front." + ] + }, + { + "id": "quant-arithmetic-exponents-roots-0021", + "section": "quant", + "topic": "arithmetic", + "subtopic": "exponents-roots", + "type": "problem-solving", + "difficulty": "medium", + "tags": [ + "exponents", + "fractional-exponents", + "roots" + ], + "choices": { + "A": "6", + "B": "9", + "C": "18", + "D": "81", + "E": "729" + }, + "answer": "B", + "author": "openmat", + "reviewers": [], + "status": "in-review", + "prompt": "What is the value of \\(27^{2/3}\\)?", + "explanation": "A fractional exponent combines a root and a power: the denominator is the root, the numerator is the\npower. Take the root **first** to keep the numbers small:\n\n\\[27^{2/3} = \\left(27^{1/3}\\right)^{2} = \\left(\\sqrt[3]{27}\\right)^{2} = 3^{2} = 9\\]\n\nThe answer is **9**.\n\n**The traps:** choice **E** (\\(729 = 27^2\\)) ignores the cube root entirely. Choice **C (18)**\nmultiplies the base by the exponent (\\(27 \\times \\tfrac23\\)). Choice **A (6)** takes the cube root\nbut then multiplies by 2 instead of squaring.", + "hints": [ + "Rewrite the exponent as a root and a power: the bottom of the fraction is the root.", + "Cube root of 27 is a small number — find it first, then apply the remaining power." + ] + }, + { + "id": "quant-arithmetic-exponents-roots-0022", + "section": "quant", + "topic": "arithmetic", + "subtopic": "exponents-roots", + "type": "problem-solving", + "difficulty": "hard", + "tags": [ + "exponents", + "exponential-equations", + "same-base" + ], + "choices": { + "A": "2", + "B": "3", + "C": "4", + "D": "5", + "E": "7" + }, + "answer": "D", + "author": "openmat", + "reviewers": [], + "status": "in-review", + "prompt": "If \\(4^{x+1} = 8^{x-1}\\), what is the value of \\(x\\)?", + "explanation": "The bases 4 and 8 are both powers of 2, so rewrite everything with base 2:\n\n\\[4^{x+1} = \\left(2^{2}\\right)^{x+1} = 2^{2(x+1)}, \\qquad 8^{x-1} = \\left(2^{3}\\right)^{x-1} = 2^{3(x-1)}\\]\n\nWith a common base, the exponents must be equal:\n\n\\[2(x+1) = 3(x-1)\\]\n\\[2x + 2 = 3x - 3\\]\n\\[x = 5\\]\n\nThe answer is **5**.\n\n**Check:** \\(4^{6} = 4096\\) and \\(8^{4} = 4096\\). ✓\n\n**The trap:** trying to compare 4 and 8 directly, or guessing a small value, misses the key move —\nexpress both sides as powers of the same prime, then set the exponents equal.", + "hints": [ + "Both 4 and 8 are powers of 2. Rewrite each side with base 2.", + "Once the bases match, the exponents must be equal — solve the resulting linear equation." + ] + }, { "id": "quant-arithmetic-fractions-decimals-0015", "section": "quant", @@ -968,6 +1148,23 @@ "status": "in-review", "body": "## Overview\n\nA quadratic equation has the form \\(ax^2 + bx + c = 0\\). On GMAT Focus Quant, most quadratics are\nbuilt to **factor cleanly**, so factoring — not the quadratic formula — is usually the fast route.\n\n## Core concepts\n\n**Factoring \\(x^2 + bx + c\\).** Find two numbers that **multiply to \\(c\\)** and **add to \\(b\\)**.\nThen \\(x^2 + bx + c = (x + p)(x + q)\\), and the solutions make each factor zero.\n\nExample: \\(x^2 - 5x + 6\\). Two numbers multiplying to \\(+6\\) and adding to \\(-5\\) are \\(-2\\) and\n\\(-3\\), so \\((x-2)(x-3) = 0\\) and \\(x = 2\\) or \\(x = 3\\).\n\n**Sum and product shortcut.** For \\(x^2 + bx + c = 0\\):\n\n\\[\\text{sum of roots} = -b, \\qquad \\text{product of roots} = c\\]\n\nThis lets you answer \"sum/product of solutions\" questions without fully solving.\n\n**Special products** worth recognizing instantly:\n\n\\[a^2 - b^2 = (a-b)(a+b), \\quad (a+b)^2 = a^2 + 2ab + b^2, \\quad (a-b)^2 = a^2 - 2ab + b^2\\]\n\n**The quadratic formula** (fallback when factoring is ugly):\n\n\\[x = \\frac{-b \\pm \\sqrt{b^2 - 4ac}}{2a}\\]\n\n## Worked examples\n\n**Factor and solve.** \\(x^2 + 2x - 15 = 0 \\Rightarrow (x+5)(x-3) = 0 \\Rightarrow x = -5 \\text{ or } 3\\).\n\n**Difference of squares.** \\(x^2 - 49 = 0 \\Rightarrow (x-7)(x+7) = 0 \\Rightarrow x = \\pm 7\\).\n\n## Common traps\n\n- **Confusing sum and product of roots.** Sum is \\(-b\\), product is \\(c\\). Read which the question wants.\n- **Dropping a solution.** A quadratic usually has *two* roots — check whether the question wants both, their sum, or only positive values.\n- **Sign errors in factoring.** Verify by expanding your factors back out.\n\n## Key takeaways\n\n- Factor into \\((x + p)(x + q)\\) where \\(pq = c\\) and \\(p + q = b\\); each factor set to zero gives a root.\n- Sum of roots \\(= -b\\), product \\(= c\\) — a fast shortcut.\n- Recognize the difference of squares and perfect-square forms on sight." }, + { + "id": "quant-arithmetic-exponents-roots", + "section": "quant", + "topic": "arithmetic", + "subtopic": "exponents-roots", + "title": "Exponents & Roots", + "tags": [ + "exponents", + "roots", + "radicals", + "powers" + ], + "author": "openmat", + "reviewers": [], + "status": "in-review", + "body": "## Overview\n\nExponents and roots show up all over GMAT Focus Quant — inside number-properties questions, in\ndisguised equations, and as the fast way to compare very large or very small quantities. Almost\neverything reduces to a short list of rules plus one habit: **rewrite every base as a power of the\nsame prime before you do anything else.**\n\n## Core concepts\n\n**The exponent rules.** For any nonzero base and integer (or rational) exponents:\n\n- Product: \\(a^m \\cdot a^n = a^{m+n}\\) — same base, *add* exponents.\n- Quotient: \\(\\dfrac{a^m}{a^n} = a^{m-n}\\) — same base, *subtract* exponents.\n- Power of a power: \\((a^m)^n = a^{mn}\\) — *multiply* exponents.\n- Distributes over products: \\((ab)^n = a^n b^n\\).\n\n**Zero and negative exponents.**\n\n\\[a^0 = 1 \\quad (a \\ne 0), \\qquad a^{-n} = \\frac{1}{a^n}\\]\n\nA negative exponent means \"reciprocal,\" not \"negative number.\" So \\(2^{-2} = \\tfrac14\\), which is\npositive.\n\n**Roots are fractional exponents.** This is the single most useful bridge:\n\n\\[\\sqrt[n]{a} = a^{1/n}, \\qquad a^{m/n} = \\left(\\sqrt[n]{a}\\right)^m = \\sqrt[n]{a^m}\\]\n\nSo \\(27^{2/3} = \\left(27^{1/3}\\right)^2 = 3^2 = 9\\). Take the root first (smaller numbers), then the power.\n\n**Simplifying radicals.** Pull perfect-square factors out from under a square root, and combine only\n*like* radicals:\n\n\\[\\sqrt{ab} = \\sqrt{a}\\,\\sqrt{b}, \\qquad \\sqrt{50} = \\sqrt{25\\cdot 2} = 5\\sqrt{2}\\]\n\nYou can add \\(5\\sqrt2 + 3\\sqrt2 = 8\\sqrt2\\), but you **cannot** turn \\(\\sqrt2 + \\sqrt2\\) into\n\\(\\sqrt4\\).\n\n**Same-base strategy for equations.** When an equation has different bases that are all powers of one\nprime, rewrite them and set the exponents equal:\n\n\\[4^{x+1} = 8^{x-1} \\;\\Rightarrow\\; 2^{2(x+1)} = 2^{3(x-1)} \\;\\Rightarrow\\; 2x+2 = 3x-3 \\;\\Rightarrow\\; x = 5\\]\n\n## Worked examples\n\n**Combine rules.** Simplify \\((x^2)^3 \\cdot x^4\\). Power of a power gives \\(x^{6}\\); then the product\nrule adds exponents: \\(x^{6} \\cdot x^{4} = x^{10}\\).\n\n**Fractional exponent.** Evaluate \\(27^{2/3}\\). Cube root of 27 is 3; square it: \\(3^2 = 9\\).\n\n**Radicals.** Simplify \\(\\sqrt{50} + \\sqrt{18} = 5\\sqrt2 + 3\\sqrt2 = 8\\sqrt2\\).\n\n## Common traps\n\n- **Multiplying exponents when you should add.** \\(2^5 \\cdot 2^3 = 2^{8}\\), not \\(2^{15}\\). You only\n multiply exponents for a *power of a power*, \\((2^5)^3 = 2^{15}\\).\n- **Negative exponent → negative number.** \\(3^{-1} = \\tfrac13\\), a positive fraction, not \\(-3\\).\n- **Adding under the radical.** \\(\\sqrt{a} + \\sqrt{b} \\ne \\sqrt{a+b}\\). \\(\\sqrt{9} + \\sqrt{16} = 3+4 = 7\\), not \\(\\sqrt{25} = 5\\).\n- **Combining unlike bases.** \\(2^3 \\cdot 3^3\\) is \\((2\\cdot3)^3 = 6^3\\), but \\(2^3 \\cdot 3^2\\) cannot be merged into one base.\n\n## Key takeaways\n\n- Same base: add exponents to multiply, subtract to divide, multiply to raise a power to a power.\n- \\(a^0 = 1\\) and \\(a^{-n} = 1/a^n\\); negative exponents give positive reciprocals.\n- Roots are fractional exponents: \\(a^{m/n} = \\sqrt[n]{a^m}\\) — take the root first, then the power.\n- To solve exponential equations, rewrite every base as the same prime and equate the exponents." + }, { "id": "quant-arithmetic-percents-ratios", "section": "quant", diff --git a/growth/LOG.md b/growth/LOG.md new file mode 100644 index 0000000..5427794 --- /dev/null +++ b/growth/LOG.md @@ -0,0 +1,29 @@ +# Growth Log + +Running record of what each growth run produced, so runs don't repeat work. Newest first. +See [`STRATEGY.md`](./STRATEGY.md) for the playbook. **"Needs human"** = an action only the +account owner can take (publishing an external post, a decision). + +--- + +## 2026-07-21 — Bootstrap: playbook + launch drafts + contributor issues + +- **Added the growth playbook** (`STRATEGY.md`): ICP, messaging pillars, channels, the daily-run + operating procedure, metrics, guardrails, and a backlog. This is now the canonical growth guide. +- **Drafted the r/GMAT launch post** → [`posts/2026-07-21-reddit-r-gmat-launch.md`](./posts/2026-07-21-reddit-r-gmat-launch.md). + **Needs human:** review + post to r/GMAT (check subreddit self-promo rules first; flair if required). +- **Drafted the Show HN post** → [`posts/2026-07-21-show-hn.md`](./posts/2026-07-21-show-hn.md). + **Needs human:** hold until the question bank is deeper (aim ~75–100+ verified), then post from the owner's HN account. One good shot — don't waste it early. +- **Created contributor-onboarding GitHub issues** (`good first issue` / `help wanted`) — see the + issues tab. **Needs human:** add the `good first issue` and `help wanted` labels in repo settings + if they don't exist yet, and consider pinning the "Start here" issue. +- **Baseline (2026-07-21):** stars/forks/external contributors ≈ 0; 38 questions, 9 lessons in the + bank; no site analytics yet. First targets: first non-founder star, first external PR, first + user feedback issue. + +### Queued for upcoming runs (from the backlog) +- Set repo topics/description; pin a "Start here" issue. +- Product issue: add privacy-respecting analytics so traffic is measurable. +- Draft GMAT Club forum intro post. +- In-site one-click "report a bad answer" feedback link. +- Awesome-list target list + submission PRs. diff --git a/growth/STRATEGY.md b/growth/STRATEGY.md new file mode 100644 index 0000000..17c786f --- /dev/null +++ b/growth/STRATEGY.md @@ -0,0 +1,102 @@ +# OpenMat Growth Playbook + +> **This is the canonical growth strategy for OpenMat, and the operating manual for the daily +> growth run.** It plays the same role for user/contributor acquisition that +> [`curriculum.md`](../curriculum.md) plays for content: every growth run consults this file, +> executes the next highest-value item, logs it in [`LOG.md`](./LOG.md), and stops. +> +> It is intentionally public. OpenMat is an open project; building in the open is on-brand and +> costs nothing. + +## The goal + +Three outcomes, in priority order: + +1. **Users** — GMAT Focus test-takers who study on the site and come back. +2. **Contributors** — people who write/review questions and lessons, or improve the code. +3. **Feedback** — a tight loop so the product improves faster than we guess. + +Users and contributors reinforce each other: a bigger question bank attracts more studiers, and +more studiers surface more contributors and better feedback. The strategy optimizes that flywheel. + +## Who we're talking to (ICP) + +| Audience | Where they are | What they want | Our hook | +|----------|----------------|----------------|----------| +| **Cost-sensitive test-takers** | r/GMAT, GMAT Club forums, GMAT Discord servers, YouTube comments | Free, current (Focus Edition) practice with real explanations | "Free forever, open-source. No paywall, no trial." | +| **High scorers / tutors** | r/GMAT, LinkedIn, GMAT Club | To give back, build a public teaching portfolio, signal expertise | "Your name on verified questions thousands study from." | +| **OSS / edtech developers** | Hacker News, Lobsters, dev.to, GitHub | Meaningful side projects, clean codebases to contribute to | "Plain Markdown + JSON, no DB, good-first-issues, MIT/CC-BY-SA." | +| **MBA applicants (broad)** | LinkedIn, r/MBA, Twitter/X | Anything that lowers the cost of applying | "The community-built GMAT prep." | + +## Messaging pillars (use these consistently) + +1. **Free forever, genuinely open** — CC-BY-SA content, MIT code. A real alternative to $150–350 courses. +2. **Built for the current exam** — GMAT **Focus Edition**, not the retired classic format (this is a real differentiator; a lot of free material online is stale). +3. **Quality-controlled, original** — `draft → in-review → verified`; no copied GMAC content; a wrong answer is worse than no question. +4. **Yours to build on** — fork it, translate it, remix it. Contributors get real credit. + +Always link the study site () for users and the repo for contributors. + +## Channels & tactics + +**Owned / compounding (do these first — they work while we sleep):** +- **GitHub discoverability** — repo topics/tags, a crisp description, `good first issue` + `help wanted` labels, a pinned "start here" issue, badges. Gets us found by developers and shows up in GitHub search. +- **SEO-friendly content** — the study site itself; lesson pages are indexable, evergreen search bait for "free GMAT Focus [topic] practice." +- **"Awesome list" inclusion** — PRs adding OpenMat to relevant awesome-* and free-resources lists (respect each list's criteria). + +**Community (highest user intent — respect each community's self-promo rules):** +- **r/GMAT** — by far the highest-intent audience. Lead with value (a free resource + a genuine ask for feedback), never a naked ad. Read the subreddit rules each time; many require flairing self-promo and limit frequency. +- **GMAT Club forums** — long-lived threads, strong SEO. A "free open-source question bank" thread. +- **GMAT Discord / study servers** — share in resource channels, offer to take feedback. + +**Developer / launch (bursty — good for contributors & a traffic spike):** +- **Show HN** — the OSS + edtech angle. One good shot; time it when the bank is meaty enough to impress. +- **Lobsters / dev.to / Hashnode** — write-up of how it's built (Markdown-as-database, zero-dependency build). +- **Product Hunt** — later, once the site is polished and the bank is deep. + +**Direct (relationship-building):** +- **LinkedIn / X** — short build-in-public updates ("this week OpenMat added X verified questions"). Compounds slowly, reaches applicants + tutors. + +## The daily growth run: operating procedure + +Each run does **one** unit of high-value work, end to end, and stops. Don't try to do everything. + +1. **Read [`LOG.md`](./LOG.md)** to see what's already done and what's queued. Never repeat a post or re-file a duplicate issue. +2. **Pick the next item** — highest value not yet done. Rough weekly rotation to stay balanced: + - *Owned/compounding* (discoverability, README, labels, awesome-lists) — bias here early; it compounds. + - *A ready-to-publish post draft* for one channel (save under [`posts/`](./posts/), dated). + - *Contributor onboarding* — create/curate 1–3 well-scoped `good first issue`s. + - *Feedback synthesis* — read new issues/PRs/comments, distill into a short "what users are telling us" note and, if warranted, product issues. +3. **Produce the artifact** — a committed file (post draft, doc, label/README change) and/or an in-scope GitHub issue. Keep external *posting* for a human unless explicitly authorized (see guardrails). +4. **Log it** in `LOG.md` (date, what, where it lives, what a human still needs to do). +5. **Open/att­ach to the PR** for committed changes; **notify** the user with anything that needs them (posts to publish, decisions). + +## Metrics to watch (report movement, not vanity) + +- GitHub **stars, forks, unique contributors**, external issues/PRs opened. +- Study-site **traffic** (if/when analytics are added — see backlog). +- Community **engagement** (Reddit upvotes/comments, HN points, Discord reactions) on things we posted. +- **Content depth** (questions/lessons, % verified) — the product metric that makes all the above easier. + +Baseline is roughly zero today; the first job is to establish the baseline and get the first non-founder star, user, and contributor. + +## Guardrails (non-negotiable) + +- **A human publishes external posts.** Drafts are prepared here; the account owner reviews and posts. Never assume prior approval carries to a new post. +- **No spam, no astroturfing.** One genuine post per community, following its rules. Never fabricate reviews, testimonials, upvotes, or sockpuppet accounts. +- **Be transparent.** Don't hide that the project is early or that content is community/AI-assisted where a community's norms expect disclosure. +- **No impersonation** of GMAC, tutors, or any person/org. OpenMat is unaffiliated with GMAC — say so where relevant. +- **Respect copyright.** Never reproduce real GMAT questions or paid-course material anywhere, including promo. +- **GitHub actions stay in scope** (`dmdaudio/openmat`) and proportionate — a few high-quality issues, not a flood. + +## Backlog (living — check LOG.md for status) + +- [ ] Set repo topics/description + `good first issue` / `help wanted` labels; pin a "Start here" issue. +- [ ] Draft the r/GMAT launch post (value-first, feedback ask). +- [ ] Draft the Show HN post (time it for when the bank is deeper). +- [ ] Create 3–5 `good first issue`s (write one question in an uncovered subtopic; review an in-review question; small site UX fixes). +- [ ] Add privacy-respecting, self-hosted-friendly analytics to the study site (so we can measure traffic) — as a product issue. +- [ ] Draft a GMAT Club forum intro post. +- [ ] Build a "free GMAT resources" awesome-list target list and submit PRs. +- [ ] Add a lightweight in-site feedback link (GitHub issue template deep-link) so users can report bad answers in one click. +- [ ] Build-in-public LinkedIn/X update template + weekly cadence. diff --git a/growth/posts/2026-07-21-reddit-r-gmat-launch.md b/growth/posts/2026-07-21-reddit-r-gmat-launch.md new file mode 100644 index 0000000..eb25184 --- /dev/null +++ b/growth/posts/2026-07-21-reddit-r-gmat-launch.md @@ -0,0 +1,46 @@ +--- +channel: Reddit — r/GMAT +status: draft — needs human to post +suggested_flair: Study Material / Resource (check current subreddit options) +notes: > + Read r/GMAT's rules before posting — self-promo is often restricted and may need flair or a + set frequency. Post from a real account with some history, not a throwaway. Lead with value and + a genuine feedback ask, not a sell. Reply to every comment; treat it as a feedback session. +--- + +**Title:** I built a free, open-source GMAT Focus question bank + study site — would love your feedback (and questions you wish existed) + +**Body:** + +GMAT prep courses run $150–350, and a lot of the free stuff online is still written for the old +classic format. So I started **OpenMat** — a free, open-source practice bank and study site built +specifically for the **GMAT Focus Edition**. + +What's there right now: + +- A growing bank of **original** practice questions (Quant, Verbal, Data Insights) with full worked + explanations and hints — not just an answer key. +- A study site with instant feedback, a per-question timer set to GMAT pacing, and a local profile + that tracks your progress in your browser (nothing to sign up for). +- Everything tagged to a shared topic taxonomy, so you can drill a specific subtopic. + +A few honest things: + +- It's **early**. The bank is still small and growing — I'd rather say that than oversell it. +- It's **free forever** and openly licensed. No paywall, no "premium tier," no email wall. +- All content is **original** — no copied real GMAT questions (those are GMAC's). Every question + goes through a review step before it's marked verified, because a wrong answer is worse than none. +- I'm **not affiliated with GMAC** in any way. + +Study site: https://dmdaudio.github.io/OpenMat/ + +What I'd love from you: + +1. **Try a few questions and tell me where the explanations are weak or an answer looks wrong.** + That feedback is the single most useful thing right now. +2. **What topics/subtopics do you most wish had more practice?** I'll prioritize those. +3. If you scored well and want to **write or review** a few questions, the whole thing is + community-built and I'd genuinely welcome the help (there's a simple contribution guide). + +Not trying to replace your prep — just trying to make a solid free option exist for the current +exam. Thanks, and good luck to everyone testing soon. diff --git a/growth/posts/2026-07-21-show-hn.md b/growth/posts/2026-07-21-show-hn.md new file mode 100644 index 0000000..18a1c9d --- /dev/null +++ b/growth/posts/2026-07-21-show-hn.md @@ -0,0 +1,44 @@ +--- +channel: Hacker News — Show HN +status: draft — HOLD until the bank is deeper (~75–100+ verified questions), then human posts +notes: > + You get essentially one good Show HN. Time it when the site is impressive enough to convert the + traffic spike into stars/contributors. Post in the morning US Eastern on a weekday. The HN + audience skews developer, so the angle is the open, hackable architecture + the free-education + mission — not GMAT tips. Be present in the comments for the first few hours; answer technical + questions directly and honestly about how early it is. +--- + +**Title:** Show HN: OpenMat – Open-source, community-built GMAT Focus prep (free forever) + +**URL:** https://github.com/DMDaudio/OpenMat + +**Body (first comment):** + +Hi HN. OpenMat is a free, open-source practice bank and study site for the GMAT Focus Edition (the +current exam). Commercial prep courses cost $150–350, so I wanted a genuinely free, openly-licensed +alternative that anyone can study from, fork, translate, or build on. + +Architecture, since this crowd will care: + +- **Content is the database.** Every question and lesson is a single Markdown file with a YAML + front-matter block, validated against JSON Schema. No DB, no CMS. This makes every contribution a + readable pull-request diff and keeps quality review human-friendly. +- **Zero-dependency build.** A ~200-line Node script scans the content tree and emits one + `content.json` the static site consumes. Deterministic output so CI stays quiet. The site is + plain HTML/CSS/JS on GitHub Pages — KaTeX for math, a local-first profile in `localStorage` with + export/import, and optional Supabase sync that's off by default (no server to run). +- **Quality workflow.** Content moves `draft → in-review → verified`; nothing ships as verified + until a second person checks the answer and explanation. All content is original — no copied GMAC + questions. +- **Licensing:** content CC-BY-SA-4.0, code MIT. + +It's early and the question bank is still growing — I'm posting partly to find contributors +(there are good-first-issues) and partly for feedback on the approach of treating a +prep-content library as a reviewable, forkable Git repo instead of a walled garden. + +Study site: https://dmdaudio.github.io/OpenMat/ +Repo: https://github.com/DMDaudio/OpenMat + +Not affiliated with GMAC. Happy to answer anything about the content pipeline or the local-first +data model.