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

Problem 2.1066 · medium

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

✓ 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
11✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
12✓ 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 single-change constraint and using valid labels from the fixed vocabulary.
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-09-28 — 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 2026-09-28
  • qwen3.6:27b-mlx: pass 2026-09-28
  • gpt-oss:20b: pass 2026-09-28

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 2026-09-28 with SymPy 1.14.0.