∫Calc Practice

Derivative of \( \displaystyle e^{- 3 x} \sin{\left(3 x \right)} \)

Problem 2.421 · hard

Differentiate \( \displaystyle f(x) = e^{- 3 x} \sin{\left(3 x \right)} \).
  1. \[ \frac{d}{d x} e^{- 3 x} \sin{\left(3 x \right)} \]
    derivativeStart with the derivative of the function.✓ Proved
  2. \[ = \sin{\left(3 x \right)} \frac{d}{d x} e^{- 3 x} + e^{- 3 x} \frac{d}{d x} \sin{\left(3 x \right)} \]
    productApply the product rule.✓ Proved
  3. \[ = - 3 e^{- 3 x} \sin{\left(3 x \right)} + e^{- 3 x} \frac{d}{d x} \sin{\left(3 x \right)} \]
    chainDifferentiate the first part using the chain rule.✓ Proved
  4. \[ = - 3 e^{- 3 x} \sin{\left(3 x \right)} + 3 e^{- 3 x} \cos{\left(3 x \right)} \]
    chain algebraDifferentiate the second part using the chain rule. Rearrange the terms.✓ Proved
  5. \[ = 3 \left(- \sin{\left(3 x \right)} + \cos{\left(3 x \right)}\right) e^{- 3 x} \]
    simplifyFactor out the common term.✓ Proved
Answer \( \left(- 3 \sin{\left(3 x \right)} + 3 \cos{\left(3 x \right)}\right) e^{- 3 x} \)

✓ 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
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 the product rule followed by the chain rule for each term. Each step modifies only one part of the expression or applies a single rule, and the labels are accurate.
Every verdict on record (6)
  • qwen3.6:27b-mlx: pass 2026-09-21 — The solution correctly applies the product rule followed by the chain rule for each term. Each step modifies only one part of the expression or applies a single rule, and the labels are accurate.
  • gpt-oss:20b: pass 2026-09-21
  • qwen3.6:27b-mlx: pass 2026-09-20 — The solution correctly applies the product rule and chain rule in separate steps, adhering to the one-change-per-step constraint. The labels and notes are accurate.
  • gpt-oss:20b: pass 2026-09-20
  • qwen3.6:27b-mlx: pass 2026-09-20
  • gpt-oss:20b: pass 2026-09-20

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.