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Derivative of \( \displaystyle \left(2 x - 8\right) e^{x - 3} \)

Problem 2.131 · hard

Differentiate \( \displaystyle f(x) = 2 \left(x - 4\right) e^{x - 3} \).
  1. \[ \frac{d}{d x} \left(2 x - 8\right) e^{x - 3} \]
    derivativeStart with the derivative of the function.✓ Proved
  2. \[ = 2 \frac{d}{d x} \left(x - 4\right) e^{x - 3} \]
    constant-multiplePull out the constant factor 2.✓ Proved
  3. \[ = 2 \left(x - 4\right) \frac{d}{d x} e^{x - 3} + 2 e^{x - 3} \frac{d}{d x} \left(x - 4\right) \]
    productApply the product rule.✓ Proved
  4. \[ = 2 \left(x - 4\right) \frac{d}{d x} e^{x - 3} + 2 e^{x - 3} \]
    derivativeDifferentiate the first part of the product.✓ Proved
  5. \[ = 2 \left(x - 4\right) e^{x - 3} + 2 e^{x - 3} \]
    chainApply the chain rule to the exponential term.✓ Proved
  6. \[ = 2 \left(x - 3\right) e^{x - 3} \]
    algebra simplifyFactor out the common term exp(x - 3). Simplify the expression inside the parentheses.✓ Proved
Answer \( 2 \left(x - 3\right) e^{x - 3} \)

✓ 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
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
  • deepseek-r1:70b: pass
  • qwen3.6:27b-mlx: pass
Every verdict on record (15)
  • qwen3.6:27b-mlx: pass 2026-09-20
  • gpt-oss:20b: pass 2026-09-20
  • qwen3.6:27b-mlx: pass 2026-09-20
  • gpt-oss:20b: pass 2026-09-20
  • qwen3.6:27b-mlx: pass 2026-09-19
  • deepseek-r1:70b: pass 2026-09-19
  • gpt-oss:20b: pass 2026-09-19
  • qwen3.6:27b-mlx: pass 2026-09-19
  • deepseek-r1:70b: pass 2026-09-19
  • gpt-oss:20b: pass 2026-09-19
  • qwen3.6:27b-mlx: pass 2026-09-18
  • deepseek-r1:70b: pass 2026-09-18
  • gpt-oss:20b: pass 2026-09-18
  • gpt-oss:20b: fail 2026-09-17 — Step 4’s note says “Differentiate the first part of the product,” yet the step also differentiates the second part; this misleads a student about what was done. The rule label is correct, but the explanatory note is inaccurate.
  • deepseek-r1:70b: pass 2026-09-17

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.