Derivative of \( \displaystyle \frac{5 x^{2} \left(1 - 2 \ln{\left(5 x \right)}\right)}{4} \)
Problem 2.961 · hard
Differentiate \( \displaystyle f(x) = \frac{5 x^{2} \left(1 - 2 \ln{\left(5 x \right)}\right)}{4} \).
- \[ \frac{d}{d x} \frac{5 x^{2} \left(1 - 2 \ln{\left(5 x \right)}\right)}{4} \]Start with the derivative of the function.✓ Proved
- \[ = \frac{5 \frac{d}{d x} x^{2} \left(1 - 2 \ln{\left(5 x \right)}\right)}{4} \]constant-multiplePull out the constant factor 5/4.✓ Proved
- \[ = \frac{5 x^{2} \frac{d}{d x} \left(1 - 2 \ln{\left(5 x \right)}\right)}{4} + \frac{5 \left(1 - 2 \ln{\left(5 x \right)}\right) \frac{d}{d x} x^{2}}{4} \]productApply the product rule.✓ Proved
- \[ = \frac{5 x^{2} \frac{d}{d x} \left(1 - 2 \ln{\left(5 x \right)}\right)}{4} + \frac{5 x \left(1 - 2 \ln{\left(5 x \right)}\right)}{2} \]derivativeDifferentiate the first part of the product.✓ Proved
- \[ = \frac{5 x^{2} \left(\frac{d}{d x} 1 - 2 \frac{d}{d x} \ln{\left(5 x \right)}\right)}{4} + \frac{5 x \left(1 - 2 \ln{\left(5 x \right)}\right)}{2} \]sumDifferentiate the second part of the product.✓ Proved
- \[ = - \frac{5 x^{2} \frac{d}{d x} \ln{\left(5 x \right)}}{2} + \frac{5 x \left(1 - 2 \ln{\left(5 x \right)}\right)}{2} \]derivativeDifferentiate the terms inside the parenthesis.✓ Proved
- \[ = \frac{5 x \left(1 - 2 \ln{\left(5 x \right)}\right)}{2} - \frac{x \frac{d}{d x} 5 x}{2} \]derivativeApply the chain rule to the logarithm.✓ Proved
- \[ = \frac{5 x \left(1 - 2 \ln{\left(5 x \right)}\right)}{2} - \frac{5 x}{2} \]derivative algebra algebraDifferentiate the inner function 5*x. Simplify the derivative of the inner function. 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. Final simplification.✓ Proved
Answer \( - 5 x \ln{\left(5 x \right)} \)
✓ 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 |
| 13 | ✓ 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: passqwen3.6:27b-mlx: pass
Every verdict on record (4)
qwen3.6:27b-mlx: pass 2026-09-27gpt-oss:20b: pass 2026-09-27qwen3.6:27b-mlx: fail (style) 2026-09-27 — Step 5 is labeled 'sum' but applies the linearity of the derivative operator (specifically constant-multiple and sum rules) to split the derivative of a difference; 'sum' is not a differentiation rule in the provided vocabulary, and 'constant-multiple' or 'derivative' would be more appropriate depending on granularity. Additionally, Step 7 is labeled 'derivative' but explicitly performs the chain rule expansion, which should be labeled 'chain'.gpt-oss:20b: pass 2026-09-27
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 2026-09-27 with SymPy 1.14.0.