Derivative of \( \displaystyle \frac{\left(4 x - 1\right) e^{4 x}}{2} \)
Problem 2.15 · hard
Differentiate \( \displaystyle f(x) = \frac{\left(4 x - 1\right) e^{4 x}}{2} \).
- \[ \frac{d}{d x} \frac{\left(4 x - 1\right) e^{4 x}}{2} \]derivative constant-multipleStart with the derivative of the function. Pull out the constant factor 1/2.✓ Proved
- \[ = \frac{\frac{d}{d x} \left(4 x - 1\right) e^{4 x}}{2} \]constant-multipleMove the constant to the front.✓ Proved
- \[ = \frac{\left(4 x - 1\right) \frac{d}{d x} e^{4 x}}{2} + \frac{e^{4 x} \frac{d}{d x} \left(4 x - 1\right)}{2} \]productApply the product rule.✓ Proved
- \[ = \frac{\left(4 x - 1\right) \frac{d}{d x} e^{4 x}}{2} + 2 e^{4 x} \]derivativeDifferentiate the first part of the product.✓ Proved
- \[ = 2 \left(4 x - 1\right) e^{4 x} + 2 e^{4 x} \]chainApply the chain rule to the exponential term.✓ Proved
- \[ = \frac{\left(16 x - 4\right) e^{4 x}}{2} + 2 e^{4 x} \]algebraDistribute the 4 into the parentheses.✓ Proved
- \[ = 8 x e^{4 x} \]algebra simplify simplifyExpand the expression. Combine like terms. Multiply by the constant 1/2.✓ Proved
Answer \( 8 x e^{4 x} \)
✓ 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 |
| 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 |
| 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: passdeepseek-r1:70b: passqwen3.6:27b-mlx: pass
Every verdict on record (15)
qwen3.6:27b-mlx: pass 2026-09-20gpt-oss:20b: pass 2026-09-20qwen3.6:27b-mlx: pass 2026-09-20 — The solution correctly applies the rules in a step-by-step manner, adhering to the one-change-per-step constraint and using valid labels from the fixed vocabulary.gpt-oss:20b: pass 2026-09-20qwen3.6:27b-mlx: pass 2026-09-19deepseek-r1:70b: pass 2026-09-19gpt-oss:20b: pass 2026-09-19qwen3.6:27b-mlx: pass 2026-09-19deepseek-r1:70b: pass 2026-09-19gpt-oss:20b: pass 2026-09-19qwen3.6:27b-mlx: pass 2026-09-18deepseek-r1:70b: pass 2026-09-18gpt-oss:20b: pass 2026-09-18gpt-oss:20b: pass 2026-09-16deepseek-r1:70b: pass 2026-09-16
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.