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Home›Calculus 1›L'Hôpital's rule›Problem 1.308

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

Problem 1.308 · medium

Evaluate \( \displaystyle \lim_{x \to - \frac{1}{2}} \frac{e^{2 x + 1} - 1}{2 x + 1} \).
  1. \[ \lim_{x \to - \frac{1}{2}^+}\left(\frac{e^{2 x + 1} - 1}{2 x + 1}\right) \]
    limitSet up the limit with the specified direction.✓ Proved
  2. \[ = \lim_{x \to - \frac{1}{2}^+}\left(\frac{\frac{d}{d x} \left(e^{2 x + 1} - 1\right)}{\frac{d}{d x} \left(2 x + 1\right)}\right) \]
    lhopitalApply L'Hôpital's rule since the limit is an indeterminate form 0/0.✓ Proved
  3. \[ = \lim_{x \to - \frac{1}{2}^+} e^{2 x + 1} \]
    simplify simplifyCompute the derivatives. Simplify the fraction.✓ Proved
  4. \[ = 1 \]
    limit algebra simplifyEvaluate the limit by substituting the value of x. Simplify the exponent. Final result.✓ 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 2*x + 1 = 0
undefined where Derivative(2*x + 1, x) = 0
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where Derivative(2*x + 1, x) = 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
7✓ 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 2026-10-06
  • qwen3.6:27b-mlx: pass 2026-10-06
  • qwen3.6:27b-mlx: pass 2026-10-06
  • gpt-oss:20b: pass 2026-10-06

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 2026-10-06 with SymPy 1.14.0.