Derivative of \( \displaystyle \left(2 - x\right) e^{x - 1} \)
Problem 2.1066 · medium
Differentiate \( \displaystyle f(x) = \left(2 - x\right) e^{x - 1} \).
- \[ \frac{d}{d x} \left(2 - x\right) e^{x - 1} \]Start with the derivative of the function.✓ Proved
- \[ = \frac{d}{d x} \left(- x e^{x - 1} + 2 e^{x - 1}\right) \]algebraDistribute the term (2 - x).✓ Proved
- \[ = - \frac{d}{d x} x e^{x - 1} + \frac{d}{d x} 2 e^{x - 1} \]sumApply the difference rule.✓ Proved
- \[ = - \frac{d}{d x} x e^{x - 1} + 2 \frac{d}{d x} e^{x - 1} \]constant-multiplePull out the constant factor 2.✓ Proved
- \[ = - x \frac{d}{d x} e^{x - 1} - e^{x - 1} \frac{d}{d x} x + 2 \frac{d}{d x} e^{x - 1} \]productApply the product rule to the second term.✓ Proved
- \[ = - x \frac{d}{d x} e^{x - 1} - e^{x - 1} + 2 \frac{d}{d x} e^{x - 1} \]derivativeDifferentiate x.✓ Proved
- \[ = - x e^{x - 1} \frac{d}{d x} \left(x - 1\right) + 2 e^{x - 1} \frac{d}{d x} \left(x - 1\right) - e^{x - 1} \]chainApply the chain rule to exp(x - 1).✓ Proved
- \[ = - x e^{x - 1} + e^{x - 1} \]derivative algebra algebra simplifyDifferentiate x - 1. Simplify the expression. Distribute the negative sign. Combine like terms.✓ Proved
- \[ = \left(1 - x\right) e^{x - 1} \]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
| Line | Status | Checked by | Detail |
|---|---|---|---|
| 1 | ✓ Proved | sympy 1.14.0 | line 1 is the problem as stated |
| 2 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 3 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 4 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 5 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 6 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 7 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 8 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 9 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 10 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 11 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| 12 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 |
| answer | ✓ Proved | sympy 1.14.0 | final line against the stated answer: simplify(a - b) reduced to 0 |
| answer, a second way | ✓ Proved | sympy 1.14.0 | SymPy differentiated f directly and got the stated answer |
Reviewers
gpt-oss:20b: passqwen3.6:27b-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 2026-09-28qwen3.6:27b-mlx: pass 2026-09-28gpt-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.