Math Problem Statement

Evaluate the limit of the expression as x approaches infinity: (sqrt(x + 2) - 2) / (sqrt(x + 7) - 3).

Solution

The mathematical expression provided in the image appears to be:

limx+(x+22x+73)\lim_{x \to +\infty} \left( \frac{\sqrt{x+2} - 2}{\sqrt{x+7} - 3} \right)

Steps to Solve:

  1. Substitute x+x \to +\infty: As xx approaches infinity, the dominant term in both the numerator and denominator is x\sqrt{x}. We can focus on simplifying the behavior as xx becomes very large.

  2. Simplify using the limit properties: To handle the infinity form, we multiply both the numerator and denominator by the conjugates of their respective terms to simplify the square roots:

    x+22x+73x+2+2x+2+2=(x+2)4(x+73)(x+7+3)\frac{\sqrt{x+2} - 2}{\sqrt{x+7} - 3} \cdot \frac{\sqrt{x+2} + 2}{\sqrt{x+2} + 2} = \frac{(x+2) - 4}{(\sqrt{x+7} - 3)(\sqrt{x+7} + 3)}

    Simplify each part: =x2(x+7)9=x2x2= \frac{x - 2}{(x+7) - 9} = \frac{x - 2}{x - 2}

    For large xx, this simplifies to 11, because the lower-order terms (2-2, 9-9) become negligible as xx \to \infty.

Conclusion:

limx+(x+22x+73)=1\lim_{x \to +\infty} \left( \frac{\sqrt{x+2} - 2}{\sqrt{x+7} - 3} \right) = 1


Would you like a more detailed breakdown of any step, or do you have any specific questions?

Here are five related questions to expand your understanding:

  1. What are common methods for solving limits involving infinity and square roots?
  2. How do conjugates help simplify expressions involving square roots?
  3. What is the impact of lower-order terms when evaluating limits at infinity?
  4. How would this limit change if the coefficients of xx were different inside the square roots?
  5. How would you apply L'Hopital's Rule to limits of indeterminate forms like this one?

Tip: When evaluating limits at infinity, always check if multiplying by a conjugate or simplifying leading terms makes the limit clearer.

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Math Problem Analysis

Mathematical Concepts

Limits
Infinity
Square Roots
Conjugates

Formulas

lim(x -> +∞) [sqrt(x + 2) - 2] / [sqrt(x + 7) - 3]
Multiply numerator and denominator by the conjugate: a - b / a + b

Theorems

Limit Properties
Conjugate Rationalization

Suitable Grade Level

Grades 11-12