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Derivative of \( \displaystyle \left(5 x - 2\right) e^{5 x - 1} \)

Problem 2.982 · medium

Differentiate \( \displaystyle f(x) = \left(5 x - 2\right) e^{5 x - 1} \).
  1. \[ \frac{d}{d x} \left(5 x - 2\right) e^{5 x - 1} \]
    Start with the derivative of the function.✓ Proved
  2. \[ = \frac{d}{d x} \left(5 x e^{5 x - 1} - 2 e^{5 x - 1}\right) \]
    algebraDistribute the term.✓ Proved
  3. \[ = \frac{d}{d x} 5 x e^{5 x - 1} - \frac{d}{d x} 2 e^{5 x - 1} \]
    sumApply the sum rule.✓ Proved
  4. \[ = 5 \frac{d}{d x} x e^{5 x - 1} - 2 \frac{d}{d x} e^{5 x - 1} \]
    constant-multipleFactor out the constants.✓ Proved
  5. \[ = 5 x \frac{d}{d x} e^{5 x - 1} + 5 e^{5 x - 1} \frac{d}{d x} x - 2 \frac{d}{d x} e^{5 x - 1} \]
    productApply the product rule to the first term.✓ Proved
  6. \[ = 5 x \frac{d}{d x} e^{5 x - 1} + 5 e^{5 x - 1} - 2 \frac{d}{d x} e^{5 x - 1} \]
    derivativeDifferentiate x.✓ Proved
  7. \[ = 25 x e^{5 x - 1} - 5 e^{5 x - 1} \]
    chain product algebraDifferentiate the exponential term using the chain rule. Distribute the 5 into the parentheses. Combine like terms.✓ Proved
  8. \[ = \left(25 x - 5\right) e^{5 x - 1} \]
    simplifyFactor out the common term.✓ Proved
Answer \( \left(25 x - 5\right) e^{5 x - 1} \)

✓ 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
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
9✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
10✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
answer, a second way✓ Provedsympy 1.14.0SymPy differentiated f directly and got the stated answer

Reviewers

  • gpt-oss:20b: pass — Step 8 is labeled "product" but it is a simple algebraic distribution of the constant 5 into the parentheses; the correct label would be "algebra".
  • qwen3.6:27b-mlx: fail (style) — Step 8 is labeled 'product' but performs algebraic distribution (multiplying a constant into a sum), which should be labeled 'algebra'. Step 7 is labeled 'chain' but effectively applies the exponential derivative rule (which implies the chain rule); while 'chain' is acceptable for the inner derivative, the step also simplifies the coefficient, making it slightly ambiguous, but the primary defect is the mislabeling in Step 8.
Every verdict on record (4)
  • qwen3.6:27b-mlx: fail (style) 2026-09-27 — Step 8 is labeled 'product' but performs algebraic distribution (multiplying a constant into a sum), which should be labeled 'algebra'. Step 7 is labeled 'chain' but effectively applies the exponential derivative rule (which implies the chain rule); while 'chain' is acceptable for the inner derivative, the step also simplifies the coefficient, making it slightly ambiguous, but the primary defect is the mislabeling in Step 8.
  • gpt-oss:20b: pass 2026-09-27 — Step 8 is labeled "product" but it is a simple algebraic distribution of the constant 5 into the parentheses; the correct label would be "algebra".
  • qwen3.6:27b-mlx: fail (style) 2026-09-27 — Step 8 is labeled 'product' but performs algebraic distribution (multiplying a constant into a sum), which should be labeled 'algebra'. Step 10 is labeled 'simplify' but performs factoring, which is better described as 'algebra' or 'rewrite'.
  • gpt-oss:20b: pass 2026-09-27

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 2026-09-27 with SymPy 1.14.0.