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The squeeze theorem

Problem 1.702 · medium

Use the squeeze theorem to find \( \displaystyle \lim_{n \to \infty} \frac{\sin{\left(n \right)}}{n^{2}} \).
  1. Since −1 ≤ sin(·) ≤ 1, the expression lies between -1/n**2 and n**(-2).
    Reviewed
  2. \[ \lim_{n \to \infty}\left(- \frac{1}{n^{2}}\right) = 0 \]
    The lower bound's limit.✓ Proved
  3. \[ \lim_{n \to \infty} \frac{1}{n^{2}} = 0 \]
    The upper bound's limit, the same.✓ Proved
  4. Both bounds tend to the same value, so the expression trapped between them does too.
    Reviewed
Answer \( 0 \)

Lines: 2 proved, 2 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. How we verify

The full receipt
LineStatusChecked byDetail
1Reviewedreviewers: gpt-oss:20b, qwen3.6:27b-mlxa sentence; read, not computed
2✓ Provedsympy 1.14.0simplify(lhs - rhs) reduced to 0
3✓ Provedsympy 1.14.0simplify(lhs - rhs) reduced to 0
4Reviewedreviewers: gpt-oss:20b, qwen3.6:27b-mlxa sentence; read, not computed
answer, a second way✓ Checked independentlysympy 1.14.0 + mpmath 1.3.0the expression evaluated ever closer to the limit point

Reviewers

  • gpt-oss:20b: pass
  • qwen3.6:27b-mlx: pass — The solution correctly applies the Squeeze Theorem by bounding the sine function and showing both bounds converge to 0.
Every verdict on record (6)
  • qwen3.6:27b-mlx: pass 2026-10-18 — The solution correctly applies the Squeeze Theorem by bounding the sine function and showing both bounds converge to 0.
  • gpt-oss:20b: pass 2026-10-18
  • qwen3.6:27b-mlx: pass 2026-10-16 — The solution correctly applies the Squeeze Theorem by bounding the sine function and showing both bounds converge to 0.
  • gpt-oss:20b: pass 2026-10-16
  • qwen3.6:27b-mlx: inconclusive 2026-10-15 — reviewer response could not be parsed: { "verdict": "fail", "severity": "error", "notes": "The solution incorrectly states the upper bound as n**(-2) instead of 1/n**2 (or n**(-2) is correct, but the lower bound is -1/n**2, so the interval
  • gpt-oss:20b: pass 2026-10-15

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/squeeze_theorem, checked 2026-10-18 with SymPy 1.14.0.