Derivative of \( \displaystyle - \cos{\left(5 x - 1 \right)} \)
Problem 2.596 · easy
Differentiate \( \displaystyle f(x) = - \cos{\left(5 x - 1 \right)} \).
- \[ \frac{d}{d x} \left(- \cos{\left(5 x - 1 \right)}\right) \]Start with the derivative of the function.✓ Proved
- \[ = - \frac{d}{d x} \cos{\left(5 x - 1 \right)} \]constantPull the constant -1 out of the derivative.✓ Proved
- \[ = \sin{\left(5 x - 1 \right)} \frac{d}{d x} \left(5 x - 1\right) \]trig algebraApply the derivative rule for cosine. Simplify the signs.✓ Proved
- \[ = \left(- \frac{d}{d x} 1 + \frac{d}{d x} 5 x\right) \sin{\left(5 x - 1 \right)} \]sumSplit the derivative of the inner function.✓ Proved
- \[ = \sin{\left(5 x - 1 \right)} \frac{d}{d x} 5 x \]constant algebraThe derivative of a constant is zero. Simplify the expression.✓ Proved
- \[ = 5 \sin{\left(5 x - 1 \right)} \]derivative algebraDifferentiate the linear term 5*x. Final simplified form.✓ Proved
Answer \( 5 \sin{\left(5 x - 1 \right)} \)
✓ 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 2026-09-21gpt-oss:20b: pass 2026-09-21qwen3.6:27b-mlx: pass 2026-09-21gpt-oss:20b: pass 2026-09-21
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.