Math Problem Statement

the functions f and g are defines as follows: f(x) = (x+3) / (x^2-6x+9) , g(x) = (x-7)(x^2-49), for each function, find the domain, write each answer as an interval or union of intervals

Solution

To find the domain of the functions f(x)f(x) and g(x)g(x), we need to identify the values of xx for which each function is defined. This typically involves finding where the denominator is zero (for rational functions) or where the expression is undefined (for polynomials).

Function f(x)=x+3x26x+9f(x) = \frac{x+3}{x^2 - 6x + 9}

  1. Identify the denominator: x26x+9x^2 - 6x + 9.

  2. Set the denominator equal to zero and solve for xx: x26x+9=0x^2 - 6x + 9 = 0 Factor the quadratic expression: (x3)(x3)=0(x - 3)(x - 3) = 0 So, x=3x = 3.

    This means f(x)f(x) is undefined when x=3x = 3.

  3. Domain of f(x)f(x): The function is defined for all real numbers except x=3x = 3.

    • In interval notation, the domain of f(x)f(x) is (,3)(3,)\boxed{(-\infty, 3) \cup (3, \infty)}.

Function g(x)=(x7)(x249)g(x) = (x-7)(x^2 - 49)

  1. Simplify the expression: Note that x249x^2 - 49 can be factored as (x7)(x+7)(x - 7)(x + 7). So, g(x)=(x7)(x7)(x+7)=(x7)2(x+7)g(x) = (x-7)(x-7)(x+7) = (x-7)^2(x+7)

  2. Identify any restrictions: Since g(x)g(x) is a polynomial function, it is defined for all real values of xx. There are no restrictions.

  3. Domain of g(x)g(x): The domain of g(x)g(x) is all real numbers.

    • In interval notation, the domain of g(x)g(x) is (,)\boxed{(-\infty, \infty)}.

Summary

  • The domain of f(x)=x+3x26x+9f(x) = \frac{x+3}{x^2 - 6x + 9} is (,3)(3,)(-\infty, 3) \cup (3, \infty).
  • The domain of g(x)=(x7)(x249)g(x) = (x-7)(x^2 - 49) is (,)(-\infty, \infty).

Would you like further details or have any questions?

Relative Questions:

  1. How do you determine the domain of a rational function?
  2. What is the process for factoring quadratic expressions?
  3. How do you identify when a polynomial function is defined for all real numbers?
  4. What are the implications of having a function with a domain of all real numbers?
  5. How does the presence of a square in the denominator affect the domain of a function?

Tip:

When factoring a quadratic expression, always check for perfect square trinomials, as they simplify the factorization process significantly.

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Math Problem Analysis

Mathematical Concepts

Rational Functions
Polynomial Functions
Quadratic Equations

Formulas

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Theorems

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Suitable Grade Level

Grades 10-12