∫Calc Practice

Derivative of \( \displaystyle \frac{e^{4 x}}{4 x + 1} \)

Problem 2.638 · hard

Differentiate \( \displaystyle f(x) = \frac{e^{4 x}}{4 x + 1} \).
  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
  2. \[ = e^{4 x} \frac{d}{d x} \frac{1}{4 x + 1} + \frac{\frac{d}{d x} e^{4 x}}{4 x + 1} \]
    productApply the product rule.✓ Proved
  3. \[ = e^{4 x} \frac{d}{d x} \frac{1}{4 x + 1} + \frac{4 e^{4 x}}{4 x + 1} \]
    derivativeDifferentiate the first part of the product.✓ Proved
  4. \[ = \frac{4 e^{4 x}}{4 x + 1} - \frac{e^{4 x} \frac{d}{d x} \left(4 x + 1\right)}{\left(4 x + 1\right)^{2}} \]
    chainApply the chain rule to the second part.✓ Proved
  5. \[ = \frac{4 e^{4 x}}{4 x + 1} - \frac{4 e^{4 x}}{\left(4 x + 1\right)^{2}} \]
    derivative algebraDifferentiate the inner function 4*x + 1. Rewrite the negative exponents as denominators.✓ Proved
  6. \[ = \frac{4 \left(4 x + 1\right) e^{4 x} - 4 e^{4 x}}{\left(4 x + 1\right)^{2}} \]
    algebraCombine the terms over a common denominator.✓ Proved
  7. \[ = \frac{16 x e^{4 x}}{\left(4 x + 1\right)^{2}} \]
    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
LineStatusChecked byDetail
1✓ Provedsympy 1.14.0line 1 is the problem as stated
2✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x + 1 = 0
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x + 1 = 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x + 1 = 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x + 1 = 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x + 1 = 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x + 1 = 0
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x + 1 = 0
9✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 4*x + 1 = 0
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
undefined where 4*x + 1 = 0
answer, a second way✓ Provedsympy 1.14.0SymPy differentiated f directly and got the stated answer

Reviewers

  • gpt-oss:20b: pass
  • qwen3.6:27b-mlx: pass
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-09-21
  • gpt-oss:20b: pass 2026-09-21
  • qwen3.6:27b-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.