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

Problem 2.1198 · medium

Differentiate \( \displaystyle f(x) = \left(\frac{1}{5} - x\right) e^{5 x} \).
  1. \[ \frac{d}{d x} \left(\frac{1}{5} - x\right) e^{5 x} \]
    Start with the derivative of the function.✓ Proved
  2. \[ = \frac{d}{d x} \left(- x e^{5 x} + \frac{e^{5 x}}{5}\right) \]
    algebraDistribute the exponential term.✓ Proved
  3. \[ = - \frac{d}{d x} x e^{5 x} + \frac{d}{d x} \frac{e^{5 x}}{5} \]
    sumApply the difference rule.✓ Proved
  4. \[ = - \frac{d}{d x} x e^{5 x} + \frac{\frac{d}{d x} e^{5 x}}{5} \]
    constant-multipleFactor out the constant 1/5.✓ Proved
  5. \[ = - x \frac{d}{d x} e^{5 x} - e^{5 x} \frac{d}{d x} x + \frac{\frac{d}{d x} e^{5 x}}{5} \]
    productApply the product rule to the second term.✓ Proved
  6. \[ = - x \frac{d}{d x} e^{5 x} - e^{5 x} + \frac{\frac{d}{d x} e^{5 x}}{5} \]
    derivativeDifferentiate x.✓ Proved
  7. \[ = - 5 x e^{5 x} \]
    chain algebra algebra simplifyDifferentiate the exponential term using the chain rule. Simplify the coefficients. Distribute the negative sign. Combine like terms.✓ Proved
Answer \( - 5 x e^{5 x} \)

✓ 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
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
  • qwen3.6:27b-mlx: pass — The solution correctly applies differentiation rules step-by-step, adhering to the one-change-per-step constraint and using valid labels from the fixed vocabulary.
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-09-29 — The solution correctly applies differentiation rules step-by-step, adhering to the one-change-per-step constraint and using valid labels from the fixed vocabulary.
  • gpt-oss:20b: pass 2026-09-29
  • qwen3.6:27b-mlx: pass 2026-09-29 — The solution correctly applies differentiation rules step-by-step, adhering to the single-change constraint and using valid labels from the fixed vocabulary.
  • gpt-oss:20b: pass 2026-09-29

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 2026-09-29 with SymPy 1.14.0.