Math Problem Statement

Given f(x) = 5x^2 / (x^2 - 9), determine the domain, vertical asymptotes, and horizontal asymptotes of f(x).

Solution

Let's solve each part of the question for the given function f(x)=5x2x29f(x) = \frac{5x^2}{x^2 - 9}:


Part (a): Domain of f(x)f(x)

The function is undefined where the denominator equals zero. Set the denominator equal to zero: x29=0    x2=9    x=±3x^2 - 9 = 0 \implies x^2 = 9 \implies x = \pm 3 Thus, the domain of f(x)f(x) is all real numbers except x=3x = 3 and x=3x = -3.

Domain in interval notation: (,3)(3,3)(3,)(-\infty, -3) \cup (-3, 3) \cup (3, \infty)


Part (b): Vertical Asymptotes

Vertical asymptotes occur where the denominator equals zero and the numerator is not zero. As determined earlier, the denominator is zero at x=±3x = \pm 3.

For x=±3x = \pm 3: Denominator: x29=0,Numerator: 5x20\text{Denominator: } x^2 - 9 = 0, \quad \text{Numerator: } 5x^2 \neq 0 Since the numerator is nonzero at these points, there are vertical asymptotes at: x=3andx=3x = 3 \quad \text{and} \quad x = -3


Part (c): Horizontal Asymptotes

Horizontal asymptotes are determined by the degrees of the numerator and denominator.

  • Degree of numerator: 2 (from 5x25x^2)
  • Degree of denominator: 2 (from x29x^2 - 9)

Since the degrees are equal, the horizontal asymptote is found by dividing the leading coefficients: y=Leading coefficient of numeratorLeading coefficient of denominator=51=5y = \frac{\text{Leading coefficient of numerator}}{\text{Leading coefficient of denominator}} = \frac{5}{1} = 5 Thus, the horizontal asymptote is: y=5y = 5


Final Summary:

  1. Domain: (,3)(3,3)(3,)(-\infty, -3) \cup (-3, 3) \cup (3, \infty)
  2. Vertical asymptotes: x=3x = 3 and x=3x = -3
  3. Horizontal asymptote: y=5y = 5

Would you like further clarification or detailed steps for any part?
Here are 5 related questions for practice:

  1. What happens to the graph of f(x)f(x) as x3+x \to 3^+ and x3x \to 3^-?
  2. Determine the slant asymptote if the degrees of numerator and denominator differed by 1.
  3. For what values of xx does f(x)=0f(x) = 0?
  4. How does f(x)f(x) behave as x±x \to \pm \infty?
  5. How would the domain change if the denominator were x29xx^2 - 9x?

Tip: Always check the numerator when identifying vertical asymptotes to ensure it's nonzero!

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Math Problem Analysis

Mathematical Concepts

Rational Functions
Domain and Range
Asymptotes

Formulas

Vertical asymptotes occur where the denominator is zero, provided the numerator is non-zero.
Horizontal asymptotes depend on the degree of the numerator and denominator.

Theorems

Domain Exclusion Theorem: A function is undefined where its denominator is zero.
Asymptote Behavior: Horizontal asymptotes occur when the degrees of numerator and denominator are equal or unequal by specific rules.

Suitable Grade Level

Grades 10-12