Derivative of \( \displaystyle x e^{4 x} - \frac{e^{4 x}}{4} \)
Problem 2.1751 · hard
Differentiate \( \displaystyle f(x) = x e^{4 x} - \frac{e^{4 x}}{4} \).
- \[ \frac{d}{d x} \left(x e^{4 x} - \frac{e^{4 x}}{4}\right) \]Start with the derivative of the function.✓ Proved
- \[ = \frac{d}{d x} x e^{4 x} - \frac{d}{d x} \frac{e^{4 x}}{4} \]sum constantApply the sum rule. Factor out the constant 1/4.✓ Proved
- \[ = x \frac{d}{d x} e^{4 x} + e^{4 x} \frac{d}{d x} x - \frac{d}{d x} \frac{e^{4 x}}{4} \]productApply the product rule to the first term.✓ Proved
- \[ = x \frac{d}{d x} e^{4 x} + e^{4 x} - \frac{d}{d x} \frac{e^{4 x}}{4} \]derivative simplifyDifferentiate x. Simplify the first term.✓ Proved
- \[ = 4 x e^{4 x} + e^{4 x} - \frac{d}{d x} \frac{e^{4 x}}{4} \]chain algebraDifferentiate exp(4*x) using the chain rule. Simplify the second term.✓ Proved
- \[ = 4 x e^{4 x} \]chain algebra simplifyDifferentiate the last term using the chain rule. Simplify the last term. Combine like terms.✓ Proved
Answer \( 4 x e^{4 x} \)
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. The reviewers disagree about how one step is explained; every verdict is in the receipt.
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 |
| 3 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 4 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 5 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 6 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 7 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 8 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 9 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 10 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 11 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| answer | ✓ Proved | sympy 1.14.0 | final line against the stated answer: simplify(a - b) reduced to 0 |
| 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: fail (error) — Step 3 is labeled 'constant' but does not apply the constant multiple rule (which would pull 1/4 out of the derivative); it merely rewrites the term algebraically, so the label is incorrect. Step 9 is labeled 'chain' but applies the constant multiple rule and the chain rule simultaneously to the term 1/4 * exp(4*x), violating the one-rule-per-step constraint.
Every verdict on record (4)
gpt-oss:20b: pass 2026-10-07qwen3.6:27b-mlx: fail (error) 2026-10-07 — Step 3 is labeled 'constant' but does not apply the constant multiple rule (which would pull 1/4 out of the derivative); it merely rewrites the term algebraically, so the label is incorrect. Step 9 is labeled 'chain' but applies the constant multiple rule and the chain rule simultaneously to the term 1/4 * exp(4*x), violating the one-rule-per-step constraint.gpt-oss:20b: pass 2026-10-07qwen3.6:27b-mlx: fail (error) 2026-10-07 — Step 3 is labeled 'constant' but does not apply the constant multiple rule (which would factor out 1/4); it merely rewrites the term, so the label is incorrect. Step 9 is labeled 'chain' but applies both the constant multiple rule and the chain rule simultaneously, violating the one-rule-per-step constraint.
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 2026-10-07 with SymPy 1.14.0.