Derivative of \( \displaystyle \frac{e^{4 x}}{4 x + 1} \)
Problem 2.638 · hard
Differentiate \( \displaystyle f(x) = \frac{e^{4 x}}{4 x + 1} \).
- \[ \frac{d}{d x} \frac{e^{4 x}}{4 x + 1} \]rewriteStart with the derivative of the function. Rewrite the denominator using a negative exponent.✓ Proved
- \[ = e^{4 x} \frac{d}{d x} \frac{1}{4 x + 1} + \frac{\frac{d}{d x} e^{4 x}}{4 x + 1} \]productApply the product rule.✓ Proved
- \[ = e^{4 x} \frac{d}{d x} \frac{1}{4 x + 1} + \frac{4 e^{4 x}}{4 x + 1} \]derivativeDifferentiate the first part of the product.✓ Proved
- \[ = \frac{4 e^{4 x}}{4 x + 1} - \frac{e^{4 x} \frac{d}{d x} \left(4 x + 1\right)}{\left(4 x + 1\right)^{2}} \]chainApply the chain rule to the second part.✓ Proved
- \[ = \frac{4 e^{4 x}}{4 x + 1} - \frac{4 e^{4 x}}{\left(4 x + 1\right)^{2}} \]derivative algebraDifferentiate the inner function 4*x + 1. Rewrite the negative exponents as denominators.✓ Proved
- \[ = \frac{4 \left(4 x + 1\right) e^{4 x} - 4 e^{4 x}}{\left(4 x + 1\right)^{2}} \]algebraCombine the terms over a common denominator.✓ Proved
- \[ = \frac{16 x e^{4 x}}{\left(4 x + 1\right)^{2}} \]simplifySimplify the numerator by distributing and canceling terms.✓ Proved
Answer \( \frac{16 x e^{4 x}}{\left(4 x + 1\right)^{2}} \)
✓ 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 undefined where 4*x + 1 = 0 |
| 3 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 1 = 0 |
| 4 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 1 = 0 |
| 5 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 1 = 0 |
| 6 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 1 = 0 |
| 7 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 1 = 0 |
| 8 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 1 = 0 |
| 9 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 undefined where 4*x + 1 = 0 |
| answer | ✓ Proved | sympy 1.14.0 | final line against the stated answer: simplify(a - b) reduced to 0 undefined where 4*x + 1 = 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: pass
Every verdict on record (4)
qwen3.6:27b-mlx: pass 2026-09-21gpt-oss:20b: pass 2026-09-21qwen3.6:27b-mlx: pass 2026-09-21 — The solution correctly applies the product rule, chain rule, and algebraic simplification steps. Each step changes only one aspect of the expression and uses valid labels from the provided vocabulary.gpt-oss:20b: pass 2026-09-21
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.