Integral of \( \displaystyle 9 x^{2} e^{3 x} \)
Problem 4.560 · medium
Find \( \displaystyle \int 9 x^{2} e^{3 x} \, dx \). (Omit the constant of integration.)
- \[ \int 9 x^{2} e^{3 x}\, dx \]integralStart with the integral of the given function.✓ Proved
- \[ = 9 \int x^{2} e^{3 x}\, dx \]linearityFactor out the constant 9.✓ Proved
- \[ = 3 x^{2} e^{3 x} - 3 \int 2 x e^{3 x}\, dx \]parts algebraApply integration by parts with u = x**2 and dv = exp(3*x)dx. Distribute the 9 and simplify the fraction.✓ Proved
- \[ = 3 x^{2} e^{3 x} - 6 \int x e^{3 x}\, dx \]algebraFactor out the 2 from the integral.✓ Proved
- \[ = 3 x^{2} e^{3 x} - 2 x e^{3 x} + 2 \int e^{3 x}\, dx \]parts algebraApply integration by parts to the remaining integral with u = x and dv = exp(3*x)dx. Distribute the -6 and simplify the terms.✓ Proved
- \[ = 3 x^{2} e^{3 x} - 2 x e^{3 x} + \frac{2 e^{3 x}}{3} \]antiderivativeEvaluate the final integral.✓ Proved
- \[ = \left(3 x^{2} - 2 x + \frac{2}{3}\right) e^{3 x} \]simplifyFactor out the common exponential term.✓ Proved
Answer \( \frac{\left(9 x^{2} - 6 x + 2\right) e^{3 x}}{3} + C \)
✓ 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 |
| 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 the stated antiderivative back to the integrand |
Reviewers
gpt-oss:20b: passqwen3.6:27b-mlx: pass — The solution correctly applies integration by parts twice and handles algebraic simplifications in single-rule steps. All labels are appropriate and the logic is sound.
Every verdict on record (4)
gpt-oss:20b: pass 2026-10-07qwen3.6:27b-mlx: pass 2026-10-07 — The solution correctly applies integration by parts twice and handles algebraic simplifications in single-rule steps. All labels are appropriate and the logic is sound.qwen3.6:27b-mlx: pass 2026-10-07 — The solution correctly applies integration by parts twice and handles algebraic simplifications properly. Each step changes only one aspect of the expression and uses valid labels from the fixed vocabulary.gpt-oss:20b: pass 2026-10-07
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 2026-10-07 with SymPy 1.14.0.