Question

Difficulty: EasyLimits and Continuity of Functions

Evaluate the limit lim⁡x→2x2−4x−2\lim_{x \to 2} \frac{x^2 - 4}{x - 2}. What is the numerical value of this limit?

Answer: 4

Answer

The value of the limit is 44.
Direct substitution of x=2x = 2 produces the indeterminate form 00\frac{0}{0}. Factoring the numerator gives (x−2)(x+2)x−2\frac{(x-2)(x+2)}{x-2}. Canceling the non-zero factor (x−2)(x-2) simplifies the expression to x+2x+2. Evaluating the limit as xx approaches 22 yields 2+2=42 + 2 = 4.

Step-by-Step Solution

1
Check the form by direct substitution of x=2x = 2
Obtained the indeterminate form 00\frac{0}{0}
Direct substitution results in division by zero, requiring algebraic simplification.
2
Factor the polynomial in the numerator
x2−4=(x−2)(x+2)x^2 - 4 = (x - 2)(x + 2)
Difference of two squares factorization allows canceling common terms.
3
Cancel the common factor (x−2)(x - 2)
(x−2)(x+2)x−2=x+2\frac{(x - 2)(x + 2)}{x - 2} = x + 2
For x≠2x \neq 2, division by (x−2)(x - 2) is valid.
4
Evaluate the simplified limit as x→2x \to 2
2+2=42 + 2 = 4
Substitute x=2x = 2 directly into the continuous polynomial x+2x + 2.

Key Concept

Evaluating indeterminate limits of the form 00\frac{0}{0} via factorization
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