Math Problem Statement

lim x >-2 (x^3+8)/(x^2-4)

Solution

To find the limit:

limx2x3+8x24\lim_{x \to -2} \frac{x^3 + 8}{x^2 - 4}

Step 1: Factor both the numerator and the denominator.

The numerator, x3+8x^3 + 8, is a sum of cubes, which can be factored as:

x3+8=(x+2)(x22x+4)x^3 + 8 = (x + 2)(x^2 - 2x + 4)

The denominator, x24x^2 - 4, is a difference of squares and can be factored as:

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

Step 2: Simplify the expression.

Now, the expression becomes:

(x+2)(x22x+4)(x+2)(x2)\frac{(x + 2)(x^2 - 2x + 4)}{(x + 2)(x - 2)}

You can cancel out the common factor of (x+2)(x + 2), provided x2x \neq -2. This simplifies to:

x22x+4x2\frac{x^2 - 2x + 4}{x - 2}

Step 3: Evaluate the limit as x2x \to -2.

Now substitute x=2x = -2 into the simplified expression:

(2)22(2)+422=4+4+44=124=3\frac{(-2)^2 - 2(-2) + 4}{-2 - 2} = \frac{4 + 4 + 4}{-4} = \frac{12}{-4} = -3

Final Answer:

limx2x3+8x24=3\lim_{x \to -2} \frac{x^3 + 8}{x^2 - 4} = -3

Would you like further details or clarification on any of the steps?


Here are 5 related questions you might find interesting:

  1. How would the limit change if the expression was x38x24\frac{x^3 - 8}{x^2 - 4}?
  2. What happens when we approach a limit that results in a 00\frac{0}{0} indeterminate form?
  3. Can you explain the significance of canceling common factors when simplifying limits?
  4. How does the limit differ when approaching from the right (x2+x \to -2^+) vs. from the left (x2x \to -2^-)?
  5. What would happen if we tried to evaluate limx2x3+8x24\lim_{x \to 2} \frac{x^3 + 8}{x^2 - 4}?

Tip: Always check for possible factorizations when encountering limits with polynomials to simplify indeterminate forms.

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Math Problem Analysis

Mathematical Concepts

Limits
Factorization
Polynomials
Indeterminate Forms

Formulas

Sum of cubes formula: a^3 + b^3 = (a + b)(a^2 - ab + b^2)
Difference of squares formula: a^2 - b^2 = (a + b)(a - b)

Theorems

Limit of a rational function
Factorization of polynomials

Suitable Grade Level

Grades 11-12