Math Problem Statement

solve the problem

Find the following limits: a) lim x→2+ (1 / (x² - 4)) b) lim x→2- (1 / (x² - 4)) c) lim x→2 (1 / (x² - 4))

Solution

The image presents a problem asking to find three different limits. Let's go through each one step by step:

Given expressions:

a) limx2+1x24\text{a) } \lim_{{x \to 2^+}} \frac{1}{{x^2 - 4}} b) limx21x24\text{b) } \lim_{{x \to 2^-}} \frac{1}{{x^2 - 4}} c) limx21x24\text{c) } \lim_{{x \to 2}} \frac{1}{{x^2 - 4}}


Factoring x24x^2 - 4:

x24=(x2)(x+2)x^2 - 4 = (x - 2)(x + 2)

This will help us analyze the limits since we know x=2x = 2 is a point where the denominator becomes zero, causing potential discontinuity.


Limit a: limx2+1x24\lim_{{x \to 2^+}} \frac{1}{{x^2 - 4}}

When xx approaches 22 from the right (2+2^+), the expression in the denominator x24=(x2)(x+2)x^2 - 4 = (x - 2)(x + 2) becomes very small and positive because:

  • x2x - 2 is small and positive for x2+x \to 2^+.
  • x+2x + 2 approaches 4 as x2+x \to 2^+.

Thus, the overall denominator is a very small positive number, which makes the fraction very large and positive.

Conclusion: limx2+1x24=+\lim_{{x \to 2^+}} \frac{1}{{x^2 - 4}} = +\infty


Limit b: limx21x24\lim_{{x \to 2^-}} \frac{1}{{x^2 - 4}}

When xx approaches 22 from the left (22^-), the expression in the denominator x24=(x2)(x+2)x^2 - 4 = (x - 2)(x + 2) becomes very small and negative because:

  • x2x - 2 is small and negative for x2x \to 2^-.
  • x+2x + 2 is still approximately 4.

Thus, the overall denominator is a very small negative number, which makes the fraction very large but negative.

Conclusion: limx21x24=\lim_{{x \to 2^-}} \frac{1}{{x^2 - 4}} = -\infty


Limit c: limx21x24\lim_{{x \to 2}} \frac{1}{{x^2 - 4}}

Since the limit as xx approaches 2 from the left (22^-) and from the right (2+2^+) yield different results (-\infty and ++\infty, respectively), the two-sided limit does not exist.

Conclusion: limx21x24 does not exist.\lim_{{x \to 2}} \frac{1}{{x^2 - 4}} \text{ does not exist.}


Would you like more details or have any questions on this explanation?

Here are some related questions:

  1. What does it mean for a limit to approach ++\infty?
  2. Why does factoring the expression help in solving the limits?
  3. How can we visualize the behavior of a function as it approaches a vertical asymptote?
  4. What are one-sided limits, and why are they important in discontinuities?
  5. What are other techniques to handle indeterminate forms in limits?

Tip: Always check for factorization or simplifications in expressions, especially around points of discontinuity or where the denominator approaches zero.

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Math Problem Analysis

Mathematical Concepts

Limits
One-Sided Limits
Discontinuities

Formulas

Factoring x² - 4 = (x - 2)(x + 2)
One-sided limit definitions

Theorems

Limit Theorem
Factoring for Limits
Discontinuity at a point

Suitable Grade Level

Grades 11-12