Math Problem Statement

Find all values x = a where the function is discontinuous. For each value of x, give the limit of the function as x approaches a. Be sure to note when the limit doesn't exist. f(x) = (x^2 - 4) / (x - 2)

Solution

The given function is:

f(x)=x24x2f(x) = \frac{x^2 - 4}{x - 2}

We need to find the values of x=ax = a where the function is discontinuous, and for each value of aa, determine the limit of the function as xx approaches aa. We also need to note if the limit does not exist.

Step 1: Simplify the function

The function f(x)=x24x2f(x) = \frac{x^2 - 4}{x - 2} contains a quadratic expression in the numerator. We can factor the numerator:

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

Thus, the function becomes:

f(x)=(x2)(x+2)x2f(x) = \frac{(x - 2)(x + 2)}{x - 2}

For x2x \neq 2, we can cancel the (x2)(x - 2) terms, and the simplified function is:

f(x)=x+2forx2f(x) = x + 2 \quad \text{for} \quad x \neq 2

Step 2: Identify discontinuity

The function is simplified to f(x)=x+2f(x) = x + 2, but there is still a discontinuity at x=2x = 2 because the original function had the factor 00\frac{0}{0} at x=2x = 2. Therefore, f(x)f(x) is discontinuous at x=2x = 2.

Step 3: Determine the limit as xx approaches 22

We now compute the limit of f(x)f(x) as xx approaches 22. Since the simplified function is f(x)=x+2f(x) = x + 2 for x2x \neq 2, we can compute the limit as:

limx2f(x)=limx2(x+2)=2+2=4\lim_{x \to 2} f(x) = \lim_{x \to 2} (x + 2) = 2 + 2 = 4

Thus, the limit of f(x)f(x) as xx approaches 22 is 44.

Conclusion:

  • The function is discontinuous at x=2x = 2.
  • The limit of the function as xx approaches 22 is 44, but the function is not defined at x=2x = 2 itself, causing the discontinuity.

Would you like more details or explanations about any specific steps?

Related Questions:

  1. What is the formal definition of a removable discontinuity?
  2. Can we make the function continuous at x=2x = 2? How?
  3. How would the behavior of the function change if the denominator was x3x - 3?
  4. What happens to the limit of the function as xx \to \infty?
  5. How would this problem change if there was an additional term like 1x2\frac{1}{x-2} added to the function?

Tip: Always check for factors that can be canceled to simplify rational functions before evaluating limits.

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Math Problem Analysis

Mathematical Concepts

Discontinuity
Limits
Factoring
Rational Functions

Formulas

Factoring quadratics: x^2 - 4 = (x - 2)(x + 2)
Limit properties

Theorems

Removable discontinuity
Limit of a function

Suitable Grade Level

Grades 10-12