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Home›Calculus 1›L'Hôpital's rule›Problem 1.376

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

Problem 1.376 · medium

Evaluate \( \displaystyle \lim_{x \to -1} \frac{- x + e^{x + 1} - 2}{\left(x + 1\right)^{2}} \).
  1. \[ \lim_{x \to -1^+}\left(\frac{- x + e^{x + 1} - 2}{\left(x + 1\right)^{2}}\right) \]
    limit algebraStart with the limit of the given function. Rewrite the numerator to group terms with (x + 1).✓ Proved
  2. \[ = \lim_{x \to -1^+}\left(\frac{\frac{d}{d x} \left(- x + e^{x + 1} - 2\right)}{\frac{d}{d x} \left(x + 1\right)^{2}}\right) \]
    lhopitalApply L'Hopital's rule since the limit is in the form 0/0.✓ Proved
  3. \[ = \lim_{x \to -1^+}\left(\frac{e^{x + 1} - 1}{2 x + 2}\right) \]
    simplifyCompute the derivatives in the numerator and denominator.✓ Proved
  4. \[ = \lim_{x \to -1^+}\left(\frac{\frac{d}{d x} \left(e^{x + 1} - 1\right)}{\frac{d}{d x} \left(2 x + 2\right)}\right) \]
    lhopitalApply L'Hopital's rule again since the limit is in the form 0/0.✓ Proved
  5. \[ = \lim_{x \to -1^+}\left(\frac{e^{x + 1}}{2}\right) \]
    simplifyCompute the derivatives.✓ Proved
  6. \[ = \frac{1}{2} \]
    limit simplifyEvaluate the limit by substituting x = -1. Simplify the final value.✓ Proved
Answer \( \frac{1}{2} \)

✓ 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 Derivative((x + 1)**2, x) = 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where Derivative((x + 1)**2, x) = 0
undefined where 2*x + 2 = 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 2*x + 2 = 0
undefined where Derivative(2*x + 2, x) = 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where Derivative(2*x + 2, x) = 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
8✓ 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)
  • gpt-oss:20b: pass 2026-10-07
  • qwen3.6:27b-mlx: pass 2026-10-07
  • qwen3.6:27b-mlx: pass 2026-10-07 — The solution correctly applies L'Hôpital's rule twice and simplifies the resulting expressions. Each step changes only one aspect of the expression and uses valid labels from the fixed vocabulary.
  • gpt-oss:20b: 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 gemma4:26b, checked 2026-10-07 with SymPy 1.14.0.