Math Problem Statement

how do you find the limit of the function f\left(x\right)=\frac{x^{2}-3x+2}{x^{2}+x-6}

Solution

To find the limit of the function f(x)=x23x+2x2+x6f(x) = \frac{x^2 - 3x + 2}{x^2 + x - 6}, you need to analyze the function's behavior as xx approaches a specific value.

Let's break it down step by step.

Step 1: Factor the numerator and denominator

First, factor both the numerator and the denominator of the function.

  • The numerator is x23x+2x^2 - 3x + 2. This can be factored as: x23x+2=(x1)(x2)x^2 - 3x + 2 = (x - 1)(x - 2)
  • The denominator is x2+x6x^2 + x - 6. This can be factored as: x2+x6=(x2)(x+3)x^2 + x - 6 = (x - 2)(x + 3)

So, the function can be rewritten as: f(x)=(x1)(x2)(x2)(x+3)f(x) = \frac{(x - 1)(x - 2)}{(x - 2)(x + 3)}

Step 2: Simplify the expression

Notice that the factor (x2)(x - 2) appears in both the numerator and the denominator. Assuming x2x \neq 2, these terms can be canceled out: f(x)=x1x+3f(x) = \frac{x - 1}{x + 3} However, it's important to remember that the original function is undefined at x=2x = 2 because the denominator becomes zero there.

Step 3: Find the limit

Now, you can find the limit as xx approaches a specific value. Let's consider two common cases:

Case 1: limx2f(x)\lim_{x \to 2} f(x)

Since the function is undefined at x=2x = 2, we instead find the limit of the simplified expression: limx2f(x)=limx2x1x+3=212+3=15\lim_{x \to 2} f(x) = \lim_{x \to 2} \frac{x - 1}{x + 3} = \frac{2 - 1}{2 + 3} = \frac{1}{5}

Case 2: limxf(x)\lim_{x \to \infty} f(x)

For very large values of xx, the behavior of the function is dominated by the highest degree terms in the numerator and the denominator. The highest degree terms are xx in the numerator and xx in the denominator: limxf(x)=limxx1x+3=limxx(11x)x(1+3x)=11=1\lim_{x \to \infty} f(x) = \lim_{x \to \infty} \frac{x - 1}{x + 3} = \lim_{x \to \infty} \frac{x(1 - \frac{1}{x})}{x(1 + \frac{3}{x})} = \frac{1}{1} = 1

Summary of Limits

  • limx2f(x)=15\lim_{x \to 2} f(x) = \frac{1}{5}
  • limxf(x)=1\lim_{x \to \infty} f(x) = 1

Would you like details on any of these steps, or do you have any other questions?


Here are 5 related questions to explore:

  1. How do you handle limits when the function is undefined at a certain point?
  2. What is the importance of factoring in finding limits?
  3. How do you approach limits that involve infinity?
  4. What is a removable discontinuity in the context of limits?
  5. How can limits be used to find the derivative of a function?

Tip: Always consider simplifying the function before applying limit rules, especially if the function is undefined at a point. This can often reveal removable discontinuities.

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Math Problem Analysis

Mathematical Concepts

Limits
Rational Functions
Factorization

Formulas

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Theorems

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Suitable Grade Level

Grades 11-12