Math Problem Statement

For the functions f(x) = x^2 / (x + 1) and g(x) = (x - 8) / (x^2 - 64), find the domain of each function and express it as an interval or union of intervals.

Solution

Let's analyze the given functions to determine their domains.

  1. Function f(x)=x2x+1f(x) = \frac{x^2}{x + 1}:

    • The domain of a rational function is all real numbers except where the denominator equals zero. For f(x)f(x), the denominator is x+1x + 1. Setting it to zero: x+1=0    x=1x + 1 = 0 \implies x = -1
    • So, the domain of f(x)f(x) is all real numbers except x=1x = -1. Domain of f(x):(,1)(1,)\text{Domain of } f(x): (-\infty, -1) \cup (-1, \infty)
  2. Function g(x)=x8x264g(x) = \frac{x - 8}{x^2 - 64}:

    • Again, the domain is all real numbers except where the denominator equals zero. The denominator x264x^2 - 64 is a difference of squares and can be factored: x264=(x8)(x+8)x^2 - 64 = (x - 8)(x + 8)
    • Set each factor equal to zero: x8=0    x=8x - 8 = 0 \implies x = 8 x+8=0    x=8x + 8 = 0 \implies x = -8
    • So, the domain of g(x)g(x) is all real numbers except x=8x = 8 and x=8x = -8. Domain of g(x):(,8)(8,8)(8,)\text{Domain of } g(x): (-\infty, -8) \cup (-8, 8) \cup (8, \infty)

Summary:

  • Domain of f(x)f(x): (,1)(1,)(-\infty, -1) \cup (-1, \infty)
  • Domain of g(x)g(x): (,8)(8,8)(8,)(-\infty, -8) \cup (-8, 8) \cup (8, \infty)

Would you like further details or clarifications? Here are 5 related questions:

  1. How do you handle rational functions with more complex denominators?
  2. What happens to the domain if a rational function has both a numerator and denominator that can be simplified?
  3. Can we use graphical methods to determine domains?
  4. What’s the significance of excluded values in a function's domain?
  5. How do vertical asymptotes relate to domain restrictions?

Tip: Always factor the denominator of a rational function to find all possible values to exclude from the domain.

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Math Problem Analysis

Mathematical Concepts

Rational Functions
Domain of Functions
Factoring

Formulas

Domain of rational function: all real numbers except where the denominator equals zero.
Difference of squares: a^2 - b^2 = (a - b)(a + b)

Theorems

Rational Functions Theorem
Difference of Squares Theorem

Suitable Grade Level

Grades 10-12