∫Calc Practice

Limit of \( \displaystyle \frac{\sqrt{2} \sqrt{x} - 3}{2 x - 9} \) as \( x \to \frac{9}{2} \)

Problem 1.127 · medium

Evaluate \( \displaystyle \lim_{x \to \frac{9}{2}} \frac{\sqrt{2} \sqrt{x} - 3}{2 x - 9} \).
  1. \[ \lim_{x \to \frac{9}{2}^+}\left(\frac{\sqrt{2} \sqrt{x} - 3}{2 x - 9}\right) \]
    limit limit algebra rewriteDefine the limit with the specified direction. Remove the direction specification for standard evaluation. Rewrite the numerator using the property sqrt(a)*sqrt(b) = sqrt(a*b). Multiply numerator and denominator by the conjugate.✓ Proved
  2. \[ = \lim_{x \to \frac{9}{2}^+} \frac{1}{\sqrt{2} \sqrt{x} + 3} \]
    algebra simplifySimplify the numerator using the difference of squares. Cancel the common factor (2*x - 9).✓ Proved
  3. \[ = \frac{1}{6} \]
    limit simplify simplifyEvaluate the limit by substituting x = 9/2. Simplify the square root. Final calculation.✓ Proved
Answer \( \frac{1}{6} \)

✓ 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 - 9 = 0
3✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 2*x - 9 = 0
4✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 2*x - 9 = 0
5✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where 2*x - 9 = 0
undefined where sqrt(2)*sqrt(x) + 3 = 0
6✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where sqrt(2)*sqrt(x) + 3 = 0
7✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
undefined where sqrt(2)*sqrt(x) + 3 = 0
8✓ Provedsympy 1.14.0simplify(a - b) reduced to 0
9✓ 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 2026-10-03 — The solution correctly applies algebraic manipulation and limit laws. Each step changes only one aspect of the expression and uses valid labels from the fixed vocabulary.
  • gpt-oss:20b: pass 2026-10-03

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.