Changing the order of integration
Problem 11.192 · hard
Evaluate \( \displaystyle \int\limits_{0}^{1}\int\limits_{x}^{1} e^{y^{2}}\, dy\, dx \) by reversing the order of integration.
- The inner integral has no elementary antiderivative in this order. The region is 0 ≤ x ≤ 1, x ≤ y ≤ 1; describe it the other way round.Reviewed
- The same region, integrated in the other order: Integral(exp(y**2), (x, 0, y), (y, 0, 1)). (The original order cannot be done by hand; the independent check below integrates it numerically.)Reviewed
- \[ \int\limits_{0}^{1}\int\limits_{0}^{y} e^{y^{2}}\, dx\, dy = - \frac{1}{2} + \frac{e}{2} \]Now the inner integral is easy, and the outer one is a substitution.✓ Proved
Answer \( - \frac{1}{2} + \frac{e}{2} \approx 0.859141 \)
✓ Nihil obstat Lines: 1 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
| Line | Status | Checked by | Detail |
|---|---|---|---|
| 1 | Reviewed | reviewers: gpt-oss:20b, qwen3.6:27b-mlx | a sentence; read, not computed |
| 2 | Reviewed | reviewers: gpt-oss:20b, qwen3.6:27b-mlx | a sentence; read, not computed |
| 3 | ✓ Proved | sympy 1.14.0 | simplify(lhs - rhs) reduced to 0 |
| answer, a second way | ✓ Checked independently | sympy 1.14.0 + mpmath 1.3.0 | numerical quadrature in the original order |
Reviewers
gpt-oss:20b: passqwen3.6:27b-mlx: pass — The solution correctly identifies the region, reverses the order of integration, and computes the result accurately.
Every verdict on record (4)
qwen3.6:27b-mlx: pass 2026-10-04 — The solution correctly identifies the region, reverses the order of integration, and computes the result accurately.gpt-oss:20b: pass 2026-10-04qwen3.6:27b-mlx: pass 2026-10-04 — The solution correctly identifies the region, reverses the order of integration, and computes the result accurately.gpt-oss:20b: pass 2026-10-04
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
generator:structured/change_order, checked 2026-10-04 with SymPy 1.14.0.