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Home›Calculus 1›L'Hôpital's rule›Problem 1.81

Limit of \( \displaystyle \frac{- 2 x + e^{2 x} - 1}{4 x^{2}} \) as \( x \to 0 \)

Problem 1.81 · medium

Evaluate \( \displaystyle \lim_{x \to 0} \frac{- 2 x + e^{2 x} - 1}{4 x^{2}} \).
  1. \[ \lim_{x \to 0^+}\left(\frac{- 2 x + e^{2 x} - 1}{4 x^{2}}\right) \]
    limit algebraStarting with the original limit expression. Rearranging the terms in the numerator.✓ Proved
  2. \[ = \lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \left(- 2 x + e^{2 x} - 1\right)}{\frac{d}{d x} 4 x^{2}}\right) \]
    lhopitalApplying L'Hopital's rule because the limit is of the form 0/0.✓ Proved
  3. \[ = \lim_{x \to 0^+}\left(\frac{2 e^{2 x} - 2}{8 x}\right) \]
    simplify factorComputing the derivatives in the numerator and denominator. Factoring out the constant 2 from the numerator.✓ Proved
  4. \[ = \lim_{x \to 0^+}\left(\frac{e^{2 x} - 1}{4 x}\right) \]
    simplifySimplifying the fraction by dividing the constants.✓ Proved
  5. \[ = \lim_{x \to 0^+}\left(\frac{\frac{d}{d x} \left(e^{2 x} - 1\right)}{\frac{d}{d x} 4 x}\right) \]
    lhopitalApplying L'Hopital's rule again as the limit is still 0/0.✓ Proved
  6. \[ = \lim_{x \to 0^+}\left(\frac{e^{2 x}}{2}\right) \]
    simplify simplifyComputing the derivatives. Simplifying the expression.✓ Proved
  7. \[ = \frac{1}{2} \]
    limitEvaluating the limit at x = 0.✓ Proved
  8. \[ = 0.5 \]
    simplifyFinal result.✓ 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 = 0
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x = 0
undefined where Derivative(4*x**2, x) = 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where Derivative(4*x**2, x) = 0
undefined where x = 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x = 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x = 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where x = 0
undefined where Derivative(4*x, x) = 0
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where Derivative(4*x, x) = 0
9✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
10✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
11✓ 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 2026-10-03
  • gpt-oss:20b: pass 2026-10-03
  • qwen3.6:27b-mlx: pass 2026-09-30
  • gpt-oss:20b: pass 2026-09-30

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 2026-10-03 with SymPy 1.14.0.