Math Problem Statement

Find the domain of the following rational functions: f(x) = x^2 / (x^2 - 9) and g(x) = x / (x - 3)

Solution

The image shows a problem that involves finding the domain of two rational functions. Let’s analyze and solve the problem step-by-step:

Given Functions

  1. f(x)=x2x29f(x) = \frac{x^2}{x^2 - 9}
  2. g(x)=xx3g(x) = \frac{x}{x - 3}

Domain of a Function

The domain of a function includes all real numbers except where the function is undefined. For rational functions, these points occur where the denominator is zero.

Step-by-step Solutions

1. Domain of f(x)=x2x29f(x) = \frac{x^2}{x^2 - 9}

  • The denominator is x29x^2 - 9.
  • Set the denominator equal to zero:
    x29=0x^2 - 9 = 0 x2=9x^2 = 9 x=±3x = \pm 3
  • Therefore, the function f(x)f(x) is undefined at x=3x = 3 and x=3x = -3.

Domain of f(x)f(x): All real numbers except x=3x = 3 and x=3x = -3.
In interval notation: (,3)(3,3)(3,)(-\infty, -3) \cup (-3, 3) \cup (3, \infty).

2. Domain of g(x)=xx3g(x) = \frac{x}{x - 3}

  • The denominator is x3x - 3.
  • Set the denominator equal to zero:
    x3=0x - 3 = 0 x=3x = 3
  • Therefore, the function g(x)g(x) is undefined at x=3x = 3.

Domain of g(x)g(x): All real numbers except x=3x = 3.
In interval notation: (,3)(3,)(-\infty, 3) \cup (3, \infty).

Conclusion

  • Domain of f(x)f(x): (,3)(3,3)(3,)(-\infty, -3) \cup (-3, 3) \cup (3, \infty)
  • Domain of g(x)g(x): (,3)(3,)(-\infty, 3) \cup (3, \infty)

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Related Questions to Explore:

  1. How do you find the domain of a function with both a numerator and denominator that are polynomials?
  2. What happens to the graph of a function at points where it is undefined?
  3. How do you find the range of a rational function?
  4. What is the difference between a vertical asymptote and a hole in the graph of a function?
  5. How does the concept of limits help in understanding points where a function is undefined?

Tip

When determining the domain of a rational function, always identify the values that make the denominator zero and exclude them from the domain.

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Math Problem Analysis

Mathematical Concepts

Algebra
Rational Functions
Domain of a Function

Formulas

Domain of a rational function: Set the denominator not equal to zero to avoid undefined values

Theorems

A function is undefined where the denominator is zero

Suitable Grade Level

Grades 9-11