∫Calc Practice

Limit of \( \displaystyle \frac{\sin^{2}{\left(x + 1 \right)}}{\left(x + 1\right)^{2}} \) as \( x \to -1 \)

Problem 1.229 · medium

Evaluate \( \displaystyle \lim_{x \to -1} \frac{\sin^{2}{\left(x + 1 \right)}}{\left(x + 1\right)^{2}} \).
  1. \[ \lim_{x \to -1^+}\left(\frac{\sin^{2}{\left(x + 1 \right)}}{\left(x + 1\right)^{2}}\right) \]
    limit algebraIdentify the limit to evaluate. Rewrite the expression as a single squared term.✓ Proved
  2. \[ = \lim_{u \to 0^+}\left(\frac{\sin^{2}{\left(u \right)}}{u^{2}}\right) \]
    substitutionLet u = x + 1, so as x approaches -1, u approaches 0.✓ Proved
  3. \[ = \left(\lim_{u \to 0^+}\left(\frac{\sin{\left(u \right)}}{u}\right)\right)^{2} \]
    limit-lawApply the power rule for limits.✓ Proved
  4. \[ = \lim_{u \to 0^+} 1 \]
    trig-limitUse the fundamental trigonometric limit sin(u)/u -> 1.✓ Proved
  5. \[ = 1 \]
    simplifyThe limit evaluates to 1.✓ Proved
Answer \( 1 \)

✓ 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
LineStatusChecked byDetail
1✓ Provedsympy 1.14.0line 1 is the problem as stated
2✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x + 1 = 0
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x + 1 = 0
undefined where u = 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where u = 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where u = 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
answer✓ Provedsympy 1.14.0final line against the stated answer: simplify(a - b) reduced to 0
answer, a second way✓ Provedsympy 1.14.0SymPy took the limit from both sides and got the stated value

Reviewers

  • gpt-oss:20b: pass
  • qwen3.6:27b-mlx: pass
Every verdict on record (4)
  • qwen3.6:27b-mlx: pass 2026-10-05
  • gpt-oss:20b: pass 2026-10-05
  • qwen3.6:27b-mlx: pass 2026-10-05 — The solution correctly applies substitution, limit laws, and the standard trigonometric limit. Each step changes only one aspect of the expression and uses valid labels from the vocabulary.
  • gpt-oss:20b: pass 2026-10-05

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 2026-10-05 with SymPy 1.14.0.