Euler's method
Problem 6.371 · medium
Use Euler's method with step size \( \displaystyle h = \frac{1}{2} \) to approximate \( \displaystyle y(1) \) for \( \displaystyle y' = t + y \), \( \displaystyle y(0) = 3 \).
- Each step follows the tangent line: yₙ₊₁ = yₙ + h·f(tₙ, yₙ), tₙ₊₁ = tₙ + h.Reviewed
- \[ 1 \cdot \frac{1}{2} \cdot 3 + 3 = \frac{9}{2} \]y1 = y0 + h·f(t0, y0) with t0 = 0, slope 3.✓ Proved
- \[ 1 \cdot \frac{1}{2} \cdot 5 + \frac{9}{2} = 7 \]y2 = y1 + h·f(t1, y1) with t1 = 1/2, slope 5.✓ Proved
Answer \( y(1) \approx 7 = 7 \)
Lines: 2 proved, 1 reviewed. 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
| Line | Status | Checked by | Detail |
|---|---|---|---|
| 1 | Reviewed | reviewers: gpt-oss:20b, qwen3.6:27b-mlx | a sentence; read, not computed |
| 2 | ✓ Proved | sympy 1.14.0 | simplify(lhs - rhs) reduced to 0 |
| 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 | the steps rerun in floating point |
Reviewers
gpt-oss:20b: passqwen3.6:27b-mlx: pass — The solution correctly applies Euler's method with the specified step size and initial conditions. The intermediate calculations and final approximation are accurate.
Every verdict on record (4)
qwen3.6:27b-mlx: pass 2026-10-11 — The solution correctly applies Euler's method with the specified step size and initial conditions. The intermediate calculations and final approximation are accurate.gpt-oss:20b: pass 2026-10-11qwen3.6:27b-mlx: inconclusive 2026-10-11 — reviewer response could not be parsed: { "verdict": "fail", "severity": "error", "notes": "The solution incorrectly calculates the slope at the second step. For y' = t + y, at t1 = 1/2 and y1 = 4.5, the slope should be 5, not 5 (wait, 0.5gpt-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
generator:structured/eulers_method, checked 2026-10-11 with SymPy 1.14.0.