Integral of \( \displaystyle \left(2 x - 1\right)^{2} e^{2 x - 1} \)
Problem 4.152 · medium
Find \( \displaystyle \int \left(2 x - 1\right)^{2} e^{2 x - 1} \, dx \). (Omit the constant of integration.)
- \[ \int \left(2 x - 1\right)^{2} e^{2 x - 1}\, dx \]integralStart with the integral of the given function.✓ Proved
- \[ = \int \left(4 x^{2} - 4 x + 1\right) e^{2 x - 1}\, dx \]algebraExpand the squared binomial.✓ Proved
- \[ = - \int 4 x e^{2 x - 1}\, dx + \int 4 x^{2} e^{2 x - 1}\, dx + \int e^{2 x - 1}\, dx \]linearityDistribute the exponential term and split the integral.✓ Proved
- \[ = \frac{e^{2 x - 1}}{2} - \int 4 x e^{2 x - 1}\, dx + \int 4 x^{2} e^{2 x - 1}\, dx \]antiderivativeIntegrate the constant term.✓ Proved
- \[ = - 2 x e^{2 x - 1} + \frac{e^{2 x - 1}}{2} + \int 4 x^{2} e^{2 x - 1}\, dx + \int 2 e^{2 x - 1}\, dx \]parts algebraApply integration by parts to the second term. Simplify the result of integration by parts.✓ Proved
- \[ = - 2 x e^{2 x - 1} + \frac{3 e^{2 x - 1}}{2} + \int 4 x^{2} e^{2 x - 1}\, dx \]antiderivative simplifyIntegrate the remaining integral. Combine the exponential terms.✓ Proved
- \[ = 2 x^{2} e^{2 x - 1} - 2 x e^{2 x - 1} + \frac{3 e^{2 x - 1}}{2} - \int 4 x e^{2 x - 1}\, dx \]partsApply integration by parts to the first term.✓ Proved
- \[ = 2 x^{2} e^{2 x - 1} - 4 x e^{2 x - 1} + \frac{3 e^{2 x - 1}}{2} + \int 2 e^{2 x - 1}\, dx \]partsApply integration by parts to the integral of x*exp(2x-1).✓ Proved
- \[ = 2 x^{2} e^{2 x - 1} - 4 x e^{2 x - 1} + \frac{5 e^{2 x - 1}}{2} \]antiderivative simplifyIntegrate the remaining exponential term. Combine all terms into the final antiderivative.✓ Proved
Answer \( \frac{\left(4 x^{2} - 8 x + 5\right) e^{2 x - 1}}{2} + C \)
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. The reviewers disagree about how one step is explained; every verdict is in the receipt.
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 the stated antiderivative back to the integrand |
Reviewers
gpt-oss:20b: passqwen3.6:27b-mlx: fail (error) — Step 9 applies integration by parts to the first term but fails to include the factor of 4 from the integrand `4*x**2`, resulting in `2*x**2` instead of `4*x**2`. This is a mathematical error in the application of the rule.
Every verdict on record (4)
qwen3.6:27b-mlx: fail (error) 2026-09-29 — Step 9 applies integration by parts to the first term but fails to include the factor of 4 from the integrand `4*x**2`, resulting in `2*x**2` instead of `4*x**2`. This is a mathematical error in the application of the rule.gpt-oss:20b: pass 2026-09-29qwen3.6:27b-mlx: fail (error) 2026-09-29 — Step 9 applies integration by parts to the first term but fails to include the factor of 4 from the integrand `4*x**2`, resulting in an incorrect coefficient for the resulting integral term. This is a mathematical error in the application of the rule.gpt-oss:20b: pass 2026-09-29
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 2026-09-29 with SymPy 1.14.0.