Derivative of \( \displaystyle \frac{x^{2}}{2} - \ln{\left(\left(2 x\right)^{x^{2}} \right)} \)
Problem 2.2049 · hard
Differentiate \( \displaystyle f(x) = \frac{x^{2}}{2} - \ln{\left(\left(2 x\right)^{x^{2}} \right)} \).
- \[ \frac{d}{d x} \left(\frac{x^{2}}{2} - \ln{\left(\left(2 x\right)^{x^{2}} \right)}\right) \]derivativeStart with the derivative of the function.✓ Proved
- \[ = \frac{d}{d x} \frac{x^{2}}{2} - \frac{d}{d x} \ln{\left(\left(2 x\right)^{x^{2}} \right)} \]sumApply the sum rule.✓ Proved
- \[ = \frac{d}{d x} \frac{x^{2}}{2} - \frac{d}{d x} x^{2} \ln{\left(2 x \right)} \]rewriteRewrite the logarithm using the property log(a^b) = b*log(a).✓ Proved
- \[ = - x^{2} \frac{d}{d x} \ln{\left(2 x \right)} - \ln{\left(2 x \right)} \frac{d}{d x} x^{2} + \frac{d}{d x} \frac{x^{2}}{2} \]productApply the product rule to the second term.✓ Proved
- \[ = - x^{2} \frac{d}{d x} \ln{\left(2 x \right)} - 2 x \ln{\left(2 x \right)} + \frac{d}{d x} \frac{x^{2}}{2} \]powerDifferentiate x**2.✓ Proved
- \[ = - 2 x \ln{\left(2 x \right)} - \frac{x \frac{d}{d x} 2 x}{2} + \frac{d}{d x} \frac{x^{2}}{2} \]chainApply the chain rule to log(2*x).✓ Proved
- \[ = - 2 x \ln{\left(2 x \right)} - x + \frac{d}{d x} \frac{x^{2}}{2} \]derivative algebra algebraDifferentiate 2*x. Simplify the expression inside the parentheses. Simplify x**2/x.✓ Proved
- \[ = - 2 x \ln{\left(2 x \right)} \]derivative algebra simplifyDifferentiate x**2/2. Distribute the negative sign. Combine like terms.✓ Proved
Answer \( - 2 x \ln{\left(2 x \right)} \)
✓ 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: passqwen3.6:27b-mlx: pass — 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 an appropriate label from the fixed vocabulary.
Every verdict on record (4)
qwen3.6:27b-mlx: pass 2026-10-11 — 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 an appropriate label from the fixed vocabulary.gpt-oss:20b: pass 2026-10-11qwen3.6:27b-mlx: pass 2026-10-11 — 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 an appropriate label from the allowed vocabulary.gpt-oss:20b: pass 2026-10-11
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 2026-10-11 with SymPy 1.14.0.