Integral of \( \displaystyle 2 x \ln{\left(2 x \right)} \)
Problem 4.732 · medium
Find \( \displaystyle \int 2 x \ln{\left(2 x \right)} \, dx \). (Omit the constant of integration.)
- \[ \int 2 x \ln{\left(2 x \right)}\, dx \]integralStart with the integral of the given function.✓ Proved
- \[ = \int 2 x \left(\ln{\left(x \right)} + \ln{\left(2 \right)}\right)\, dx \]algebraUse the logarithm product rule to expand the integrand.✓ Proved
- \[ = 2 \ln{\left(2 \right)} \int x\, dx + 2 \int x \ln{\left(x \right)}\, dx \]linearityDistribute the 2*x and split the integral into two parts.✓ Proved
- \[ = x^{2} \ln{\left(2 \right)} + 2 \int x \ln{\left(x \right)}\, dx \]antiderivativeIntegrate the first term.✓ Proved
- \[ = x^{2} \ln{\left(x \right)} + x^{2} \ln{\left(2 \right)} - 2 \int \frac{x}{2}\, dx \]parts algebra algebraApply integration by parts to the second integral with u=log(x) and dv=x dx. Simplify the integrand inside the integral. Distribute the 2 into the parentheses.✓ Proved
- \[ = x^{2} \ln{\left(x \right)} - \frac{x^{2}}{2} + x^{2} \ln{\left(2 \right)} \]antiderivative simplifyIntegrate the remaining term. Simplify the final expression.✓ Proved
Answer \( x^{2} \left(\ln{\left(2 x \right)} - \frac{1}{2}\right) + C \)
✓ 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 log is undefined for non-positive arguments |
| 3 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 4 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 5 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 6 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 7 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 8 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 9 | ✓ Proved | sympy 1.14.0 | simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| answer | ✓ Proved | sympy 1.14.0 | final line against the stated answer: simplify(a - b) reduced to 0 log is undefined for non-positive arguments |
| 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 and algebraic simplification. Each step changes only one aspect of the expression and uses valid labels from the allowed vocabulary.
Every verdict on record (4)
gpt-oss:20b: pass 2026-10-09qwen3.6:27b-mlx: pass 2026-10-09 — The solution correctly applies integration by parts and algebraic simplification. Each step changes only one aspect of the expression and uses valid labels from the allowed vocabulary.gpt-oss:20b: pass 2026-10-09qwen3.6:27b-mlx: pass 2026-10-09
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 2026-10-09 with SymPy 1.14.0.