Derivative of \( \displaystyle \frac{5 x^{2} \left(2 \ln{\left(5 x \right)} - 1\right)}{4} \)
Problem 2.238 · hard
Differentiate \( \displaystyle f(x) = \frac{5 x^{2} \left(2 \ln{\left(5 x \right)} - 1\right)}{4} \).
- \[ \frac{d}{d x} \frac{5 x^{2} \left(2 \ln{\left(5 x \right)} - 1\right)}{4} \]Start with the derivative of the function.✓ Proved
- \[ = \frac{5 \frac{d}{d x} x^{2} \left(2 \ln{\left(5 x \right)} - 1\right)}{4} \]constant-multiplePull out the constant factor 5/4.✓ Proved
- \[ = \frac{5 x^{2} \frac{d}{d x} \left(2 \ln{\left(5 x \right)} - 1\right)}{4} + \frac{5 \left(2 \ln{\left(5 x \right)} - 1\right) \frac{d}{d x} x^{2}}{4} \]productApply the product rule.✓ Proved
- \[ = \frac{5 x^{2} \frac{d}{d x} \left(2 \ln{\left(5 x \right)} - 1\right)}{4} + \frac{5 x \left(2 \ln{\left(5 x \right)} - 1\right)}{2} \]derivativeDifferentiate x**2.✓ Proved
- \[ = \frac{5 x^{2} \left(- \frac{d}{d x} 1 + \frac{d}{d x} 2 \ln{\left(5 x \right)}\right)}{4} + \frac{5 x \left(2 \ln{\left(5 x \right)} - 1\right)}{2} \]sumApply the sum rule to the second term.✓ Proved
- \[ = \frac{5 x^{2} \frac{d}{d x} \ln{\left(5 x \right)}}{2} + \frac{5 x \left(2 \ln{\left(5 x \right)} - 1\right)}{2} \]derivativeDifferentiate the terms inside the parenthesis.✓ Proved
- \[ = \frac{5 x \left(2 \ln{\left(5 x \right)} - 1\right)}{2} + \frac{5 x}{2} \]chain algebra algebraApply the chain rule to log(5*x). Simplify the derivative of the logarithm. Simplify the term x**2 * (2/x).✓ Proved
- \[ = 5 x \ln{\left(5 x \right)} \]algebra simplify simplifyDistribute 2*x into the parenthesis. Combine like terms. Multiply the remaining terms to get the final answer.✓ Proved
Answer \( 5 x \log{\left(5 x \right)} \)
✓ Nihil obstat Every line of this solution was proved by the computer algebra system SymPy. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation.
The full receipt
| Line | Status | Checked by | Detail |
|---|---|---|---|
| 1 | ✓ Proved | sympy 1.14.0 | line 1 is the problem as stated |
| 2 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 3 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 4 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 5 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 6 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 7 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 8 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 9 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 10 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 11 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 12 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| answer | ✓ Proved | sympy 1.14.0 | final line against the stated answer: simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| answer, a second way | ✓ Proved | sympy 1.14.0 | SymPy differentiated f directly and got the stated answer |
Reviewers
gpt-oss:20b: passdeepseek-r1:70b: passqwen3.6:27b-mlx: pass — The solution correctly applies differentiation rules step-by-step, adhering to the one-change-per-step constraint. All labels are appropriate for the operations performed.
Every verdict on record (12)
qwen3.6:27b-mlx: pass 2026-09-20 — The solution correctly applies differentiation rules step-by-step, adhering to the one-change-per-step constraint. All labels are appropriate for the operations performed.gpt-oss:20b: pass 2026-09-20qwen3.6:27b-mlx: pass 2026-09-20 — The solution correctly applies differentiation rules and algebraic simplifications in a step-by-step manner. Each step changes only one aspect of the expression and uses appropriate labels from the fixed vocabulary.gpt-oss:20b: pass 2026-09-20qwen3.6:27b-mlx: pass 2026-09-19 — The solution correctly applies differentiation rules step-by-step, adhering to the one-change-per-step constraint. All labels are appropriate for the transformations performed.deepseek-r1:70b: pass 2026-09-19gpt-oss:20b: pass 2026-09-19qwen3.6:27b-mlx: pass 2026-09-19 — The solution correctly applies differentiation rules step-by-step, adhering to the one-change-per-step constraint. All labels are appropriate for the operations performed.deepseek-r1:70b: pass 2026-09-19gpt-oss:20b: pass 2026-09-19gpt-oss:20b: pass 2026-09-17deepseek-r1:70b: pass 2026-09-17
Proved: SymPy reduced the difference between the two sides to zero. Checked independently: a separate
method, named above, confirmed it. Checked numerically: the two sides agree at every sampled point, which is evidence,
not proof. Reviewed: a model or a person read it; that is all a sentence can have. Solution by
gemma4:26b, checked 2026-09-26 with SymPy 1.14.0.