Derivative of \( \displaystyle \frac{\left(\sin{\left(x \right)} - \cos{\left(x \right)}\right) e^{x}}{2} \)
Problem 2.1566 · hard Beautiful
Differentiate \( \displaystyle f(x) = \frac{\left(\sin{\left(x \right)} - \cos{\left(x \right)}\right) e^{x}}{2} \).
- \[ \frac{d}{d x} \frac{\left(\sin{\left(x \right)} - \cos{\left(x \right)}\right) e^{x}}{2} \]derivativeStart with the derivative of the function.✓ Proved
- \[ = \frac{\frac{d}{d x} \left(\sin{\left(x \right)} - \cos{\left(x \right)}\right) e^{x}}{2} \]constant-multiplePull out the constant factor.✓ Proved
- \[ = \frac{\left(\sin{\left(x \right)} - \cos{\left(x \right)}\right) \frac{d}{d x} e^{x}}{2} + \frac{e^{x} \frac{d}{d x} \left(\sin{\left(x \right)} - \cos{\left(x \right)}\right)}{2} \]productApply the product rule.✓ Proved
- \[ = \frac{\left(\sin{\left(x \right)} - \cos{\left(x \right)}\right) \frac{d}{d x} e^{x}}{2} + \frac{\left(\sin{\left(x \right)} + \cos{\left(x \right)}\right) e^{x}}{2} \]derivative algebraDifferentiate the first part of the product. Simplify the signs.✓ Proved
- \[ = \frac{\left(\sin{\left(x \right)} - \cos{\left(x \right)}\right) e^{x}}{2} + \frac{\left(\sin{\left(x \right)} + \cos{\left(x \right)}\right) e^{x}}{2} \]derivativeDifferentiate the second part of the product.✓ Proved
- \[ = e^{x} \sin{\left(x \right)} \]algebra simplify simplifyFactor out exp(x). Combine like terms. Final simplification.✓ Proved
Answer \( e^{x} \sin{\left(x \right)} \)
✓ 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 |
| 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
Every verdict on record (4)
qwen3.6:27b-mlx: pass 2026-10-05gpt-oss:20b: pass 2026-10-05qwen3.6:27b-mlx: pass 2026-10-05gpt-oss:20b: pass 2026-10-05
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 2026-10-05 with SymPy 1.14.0.