∫Calc Practice

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.)
  1. \[ \int \left(2 x - 1\right)^{2} e^{2 x - 1}\, dx \]
    integralStart with the integral of the given function.✓ Proved
  2. \[ = \int \left(4 x^{2} - 4 x + 1\right) e^{2 x - 1}\, dx \]
    algebraExpand the squared binomial.✓ Proved
  3. \[ = - \int 4 x e^{2 x - 1}\, dx + \int 4 x^{2} e^{2 x - 1}\, dx + \int e^{2 x - 1}\, dx \]
    linearityDistribute the exponential term and split the integral.✓ Proved
  4. \[ = \frac{e^{2 x - 1}}{2} - \int 4 x e^{2 x - 1}\, dx + \int 4 x^{2} e^{2 x - 1}\, dx \]
    antiderivativeIntegrate the constant term.✓ Proved
  5. \[ = - 2 x e^{2 x - 1} + \frac{e^{2 x - 1}}{2} + \int 4 x^{2} e^{2 x - 1}\, dx + \int 2 e^{2 x - 1}\, dx \]
    parts algebraApply integration by parts to the second term. Simplify the result of integration by parts.✓ Proved
  6. \[ = - 2 x e^{2 x - 1} + \frac{3 e^{2 x - 1}}{2} + \int 4 x^{2} e^{2 x - 1}\, dx \]
    antiderivative simplifyIntegrate the remaining integral. Combine the exponential terms.✓ Proved
  7. \[ = 2 x^{2} e^{2 x - 1} - 2 x e^{2 x - 1} + \frac{3 e^{2 x - 1}}{2} - \int 4 x e^{2 x - 1}\, dx \]
    partsApply integration by parts to the first term.✓ Proved
  8. \[ = 2 x^{2} e^{2 x - 1} - 4 x e^{2 x - 1} + \frac{3 e^{2 x - 1}}{2} + \int 2 e^{2 x - 1}\, dx \]
    partsApply integration by parts to the integral of x*exp(2x-1).✓ Proved
  9. \[ = 2 x^{2} e^{2 x - 1} - 4 x e^{2 x - 1} + \frac{5 e^{2 x - 1}}{2} \]
    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
LineStatusChecked byDetail
1✓ Provedsympy 1.14.0line 1 is the problem as stated
2✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
9✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
10✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
11✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
12✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
answer, a second way✓ Provedsympy 1.14.0SymPy differentiated the stated antiderivative back to the integrand

Reviewers

  • gpt-oss:20b: pass
  • qwen3.6:27b-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 2026-09-29
  • 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 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.