∫Calc Practice

Integral of \( \displaystyle 2 x \sin{\left(2 x \right)} \)

Problem 4.883 · medium

Find \( \displaystyle \int 2 x \sin{\left(2 x \right)} \, dx \). (Omit the constant of integration.)
  1. \[ \int 2 x \sin{\left(2 x \right)}\, dx \]
    integralStart with the integral of the function.✓ Proved
  2. \[ = \operatorname{parts}{\left(2 x \sin{\left(2 x \right)},x,1,\sin{\left(2 x \right)},- \frac{\cos{\left(2 x \right)}}{2} \right)} \]
    partsApply integration by parts where u = 2*x and dv = sin(2*x)dx.Reviewed
  3. \[ = - x \cos{\left(2 x \right)} - \int \left(- \cos{\left(2 x \right)}\right)\, dx \]
    partsApply the integration by parts formula: integral(u dv) = u v - integral(v du).Reviewed
  4. \[ = - x \cos{\left(2 x \right)} + \int \cos{\left(2 x \right)}\, dx \]
    simplifySimplify the expression inside and outside the integral.✓ Proved
  5. \[ = - x \cos{\left(2 x \right)} + \frac{\sin{\left(2 x \right)}}{2} \]
    antiderivativeEvaluate the remaining integral.✓ Proved
Answer \( - x \cos{\left(2 x \right)} + \frac{\sin{\left(2 x \right)}}{2} + C \)

Lines: 4 proved, 2 reviewed. 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
2Reviewedreviewers: gpt-oss:20b, qwen3.6:27b-mlxsimplify left -x*cos(2*x) - parts(2*x*sin(2*x), x, 1, sin(2*x), -cos(2*x)/2) + sin(2*x)/2; no point in the sample was defined on both lines
3Reviewedreviewers: gpt-oss:20b, qwen3.6:27b-mlxsimplify left x*cos(2*x) + parts(2*x*sin(2*x), x, 1, sin(2*x), -cos(2*x)/2) - sin(2*x)/2; no point in the sample was defined on both lines
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
5✓ 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
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-10-11
  • gpt-oss:20b: pass 2026-10-11
  • qwen3.6:27b-mlx: pass 2026-10-11
  • gpt-oss:20b: pass 2026-10-11

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 2026-10-11 with SymPy 1.14.0.