Math Problem Statement

Answer

Find the limits of the function -3(x + 2) / (x^2 + 4x + 4) as x approaches -2, from both sides and overall.

Solution

Let's break down the problem visible in your image.

Problem Statement:

You are tasked with finding the limits of the function:

f(x)=3(x+2)x2+4x+4f(x) = \frac{-3(x + 2)}{x^2 + 4x + 4}

at three points:

  1. limx23(x+2)x2+4x+4\lim_{x \to -2} \frac{-3(x+2)}{x^2 + 4x + 4}
  2. limx23(x+2)x2+4x+4\lim_{x \to -2^-} \frac{-3(x+2)}{x^2 + 4x + 4} (left-hand limit)
  3. limx2+3(x+2)x2+4x+4\lim_{x \to -2^+} \frac{-3(x+2)}{x^2 + 4x + 4} (right-hand limit)

Step-by-Step Solution:

  1. Factor the denominator:

    The denominator is x2+4x+4x^2 + 4x + 4, which can be factored as:

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

    Thus, the function becomes:

    f(x)=3(x+2)(x+2)2f(x) = \frac{-3(x+2)}{(x+2)^2}

  2. Simplify the function:

    After factoring, you can cancel out one of the (x+2)(x + 2) terms from the numerator and the denominator:

    f(x)=3x+2f(x) = \frac{-3}{x + 2}

  3. Evaluate the limits:

    • limx23x+2\lim_{x \to -2} \frac{-3}{x+2}:

      As xx approaches 2-2, the denominator x+2x + 2 approaches 0. Since the numerator is 3-3, this causes the limit to go to infinity. However, we must differentiate between the left-hand and right-hand limits because the behavior is different.

    • limx23x+2\lim_{x \to -2^-} \frac{-3}{x+2} (left-hand limit):

      As xx approaches 2-2 from the left (values less than 2-2), x+2x + 2 is negative and very small. This makes the function approach ++\infty since a negative divided by a small negative number gives a positive large value.

    • limx2+3x+2\lim_{x \to -2^+} \frac{-3}{x+2} (right-hand limit):

      As xx approaches 2-2 from the right (values greater than 2-2), x+2x + 2 is positive and very small. This makes the function approach -\infty since a negative divided by a small positive number gives a large negative value.

Final Results:

  1. limx23x+2\lim_{x \to -2} \frac{-3}{x + 2} does not exist (DNE), because the left-hand and right-hand limits are not equal.
  2. limx23x+2=+\lim_{x \to -2^-} \frac{-3}{x + 2} = +\infty
  3. limx2+3x+2=\lim_{x \to -2^+} \frac{-3}{x + 2} = -\infty

Correction to the Image:

  • The correct answers should be:
    1. DNEDNE
    2. ++\infty
    3. -\infty

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

Here are five related questions you could explore:

  1. How do you differentiate between left-hand and right-hand limits?
  2. What happens when the left-hand and right-hand limits are equal?
  3. How do you factor quadratic expressions like x2+4x+4x^2 + 4x + 4?
  4. What is the formal definition of a vertical asymptote?
  5. How do limits behave near infinity?

Tip: Always check for factorizations in the denominator to simplify limits involving polynomials!

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Math Problem Analysis

Mathematical Concepts

Limits
Asymptotes
Rational Functions

Formulas

Limit of a rational function f(x) = -3(x + 2) / (x^2 + 4x + 4)
Factoring: x^2 + 4x + 4 = (x + 2)^2

Theorems

Limit Theorem: A limit exists if and only if both the left-hand and right-hand limits are equal.
Vertical Asymptote Theorem: A function has a vertical asymptote at a point if its limit approaches positive or negative infinity as x approaches the asymptote.

Suitable Grade Level

Grades 11-12