Integral of \( \displaystyle x^{2} \sin{\left(x \right)} \)
Problem 4.359 · easy
Find \( \displaystyle \int x^{2} \sin{\left(x \right)} \, dx \). (Omit the constant of integration.)
- \[ \int x^{2} \sin{\left(x \right)}\, dx \]integralStart with the integral of the integrand.✓ Proved
- \[ = - x^{2} \cos{\left(x \right)} - \int \left(- 2 x \cos{\left(x \right)}\right)\, dx \]partsApply integration by parts with u = x**2 and dv = sin(x) dx.✓ Proved
- \[ = - x^{2} \cos{\left(x \right)} + \int 2 x \cos{\left(x \right)}\, dx \]algebraSimplify the expression by distributing the negative sign.✓ Proved
- \[ = - x^{2} \cos{\left(x \right)} + 2 \int x \cos{\left(x \right)}\, dx \]linearityPull the constant 2 out of the integral.✓ Proved
- \[ = - x^{2} \cos{\left(x \right)} + 2 x \sin{\left(x \right)} - 2 \int \sin{\left(x \right)}\, dx \]parts algebraApply integration by parts again to the remaining integral with u = x and dv = cos(x) dx. Distribute the constant 2 into the parentheses.✓ Proved
- \[ = - x^{2} \cos{\left(x \right)} + 2 x \sin{\left(x \right)} + 2 \cos{\left(x \right)} \]antiderivative algebraEvaluate the integral of sin(x). Simplify the final expression.✓ Proved
Answer \( - x^{2} \cos{\left(x \right)} + 2 x \sin{\left(x \right)} + 2 \cos{\left(x \right)} + C \)
✓ 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 |
| 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 the stated antiderivative back to the integrand |
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.