Math Problem Statement

Calculate the limit algebraically. (If an answer does not exist, enter DNE.)

lim x→−2

x2 + 8x + 12

x2 + 2x

Solution

To solve the limit

limx2x2+8x+12x2+2x,\lim_{x \to -2} \frac{x^2 + 8x + 12}{x^2 + 2x},

we will first attempt to simplify the expression by factoring both the numerator and the denominator, if possible.

Step 1: Factor the numerator

The numerator is x2+8x+12x^2 + 8x + 12. We factor this quadratic:

x2+8x+12=(x+6)(x+2).x^2 + 8x + 12 = (x + 6)(x + 2).

Step 2: Factor the denominator

The denominator is x2+2xx^2 + 2x. We factor out the common factor xx:

x2+2x=x(x+2).x^2 + 2x = x(x + 2).

Step 3: Simplify the expression

Now, the original expression becomes:

(x+6)(x+2)x(x+2).\frac{(x + 6)(x + 2)}{x(x + 2)}.

We can cancel the common factor (x+2)(x + 2) from both the numerator and denominator (as long as x2x \neq -2):

x+6x.\frac{x + 6}{x}.

Step 4: Evaluate the limit

Now, we evaluate the limit as x2x \to -2:

limx2x+6x=2+62=42=2.\lim_{x \to -2} \frac{x + 6}{x} = \frac{-2 + 6}{-2} = \frac{4}{-2} = -2.

Thus, the limit is:

2.\boxed{-2}.

Would you like more details or have any further questions?

Here are 5 related questions:

  1. How do you handle limits that result in indeterminate forms like 00\frac{0}{0}?
  2. What is the definition of a limit in calculus?
  3. How do you factor quadratics quickly?
  4. What are common techniques to evaluate limits without factoring?
  5. How do you evaluate limits that approach infinity?

Tip: Always check if an expression can be simplified by factoring or canceling terms before directly substituting values in limits.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Limits
Factoring Quadratics
Simplifying Rational Expressions

Formulas

lim x→a f(x)/g(x)
Factoring: ax^2 + bx + c = (x + m)(x + n)

Theorems

Limit Laws
Factoring Theorem

Suitable Grade Level

Grades 10-12