Euler's method
Problem 6.299 · medium
Use Euler's method with step size \( \displaystyle h = \frac{1}{4} \) to approximate \( \displaystyle y(1) \) for \( \displaystyle y' = 2 t + y \), \( \displaystyle y(0) = -1 \).
- Each step follows the tangent line: yₙ₊₁ = yₙ + h·f(tₙ, yₙ), tₙ₊₁ = tₙ + h.Reviewed
- \[ -1 + 1 \cdot \frac{1}{4} \left(-1\right) = - \frac{5}{4} \]y1 = y0 + h·f(t0, y0) with t0 = 0, slope -1.✓ Proved
- \[ - \frac{5}{4} + 1 \cdot \frac{1}{4} \left(-3\right) \frac{1}{4} = - \frac{23}{16} \]y2 = y1 + h·f(t1, y1) with t1 = 1/4, slope -3/4.✓ Proved
- \[ - \frac{23}{16} + 1 \cdot \frac{1}{4} \left(-7\right) \frac{1}{16} = - \frac{99}{64} \]y3 = y2 + h·f(t2, y2) with t2 = 1/2, slope -7/16.✓ Proved
- \[ - \frac{99}{64} + 1 \cdot \frac{1}{4} \left(-3\right) \frac{1}{64} = - \frac{399}{256} \]y4 = y3 + h·f(t3, y3) with t3 = 3/4, slope -3/64.✓ Proved
Answer \( y(1) \approx - \frac{399}{256} = -1.55859 \)
✓ Nihil obstat Lines: 4 proved, 1 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 | ✓ Proved | sympy 1.14.0 | simplify(lhs - rhs) reduced to 0 |
| 3 | ✓ Proved | sympy 1.14.0 | simplify(lhs - rhs) reduced to 0 |
| 4 | ✓ Proved | sympy 1.14.0 | simplify(lhs - rhs) reduced to 0 |
| 5 | ✓ 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
Every verdict on record (4)
gpt-oss:20b: pass 2026-10-07qwen3.6:27b-mlx: pass 2026-10-07gpt-oss:20b: pass 2026-10-07qwen3.6:27b-mlx: pass 2026-10-07
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 2026-10-07 with SymPy 1.14.0.