∫Calc Practice

Integral of \( \displaystyle \left(2 x - 1\right) e^{1 - 2 x} \)

Problem 4.143 · medium

Find \( \displaystyle \int \left(2 x - 1\right) e^{1 - 2 x} \, dx \). (Omit the constant of integration.)
  1. \[ \int \left(2 x - 1\right) e^{1 - 2 x}\, dx \]
    integralStart with the integral of the given function.✓ Proved
  2. \[ = \int \left(2 x e^{1 - 2 x} - e^{1 - 2 x}\right)\, dx \]
    linearityDistribute the exponential term.✓ Proved
  3. \[ = 2 \int x e^{1 - 2 x}\, dx - \int e^{1 - 2 x}\, dx \]
    linearitySplit the integral into two parts.✓ Proved
  4. \[ = \frac{e^{1 - 2 x}}{2} + 2 \int x e^{1 - 2 x}\, dx \]
    antiderivativeEvaluate the second integral.✓ Proved
  5. \[ = - x e^{1 - 2 x} + \frac{e^{1 - 2 x}}{2} - 2 \int \left(- \frac{e^{1 - 2 x}}{2}\right)\, dx \]
    partsApply integration by parts to the first integral.✓ Proved
  6. \[ = - x e^{1 - 2 x} + \frac{e^{1 - 2 x}}{2} + \int e^{1 - 2 x}\, dx \]
    algebra algebraSimplify the expression inside the parentheses. Distribute the 2.✓ Proved
  7. \[ = - x e^{1 - 2 x} \]
    antiderivative simplifyEvaluate the remaining integral. Combine the terms.✓ Proved
Answer \( - x e^{1 - 2 x} + C \)

✓ 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
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
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: pass — The solution correctly applies linearity, integration by parts, and antiderivative rules in a step-by-step manner. Each step changes only one aspect of the expression and uses valid labels from the fixed vocabulary.
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-09-29 — The solution correctly applies linearity, integration by parts, and antiderivative rules in a step-by-step manner. Each step changes only one aspect of the expression and uses valid labels from the fixed vocabulary.
  • gpt-oss:20b: pass 2026-09-29
  • qwen3.6:27b-mlx: pass 2026-09-29 — The solution correctly applies linearity, integration by parts, and antiderivative rules in a step-by-step manner. Each step changes only one aspect of the expression and uses valid labels from the fixed vocabulary.
  • 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.