Math Problem Statement

Suppose that the functions f and g are defined as follows: f(x) = (x - 6) / (x + 4), g(x) = x / (x + 4). Find f/g. Then, give its domain using an interval or union of intervals. Simplify your answers.

Solution

The image describes two functions f(x)f(x) and g(x)g(x), and it asks to find the quotient fg(x)\frac{f}{g}(x), simplify it, and determine its domain.

Given Functions:

  • f(x)=x6x+4f(x) = \frac{x - 6}{x + 4}
  • g(x)=xx+4g(x) = \frac{x}{x + 4}

Step 1: Find fg(x)\frac{f}{g}(x)

We compute f(x)g(x)\frac{f(x)}{g(x)} as follows: f(x)g(x)=x6x+4xx+4=x6x\frac{f(x)}{g(x)} = \frac{\frac{x - 6}{x + 4}}{\frac{x}{x + 4}} = \frac{x - 6}{x}

Thus, the simplified form of fg(x)\frac{f}{g}(x) is: fg(x)=x6x\frac{f}{g}(x) = \frac{x - 6}{x}

Step 2: Domain of fg(x)\frac{f}{g}(x)

The domain of a rational function is determined by the values of xx that do not make the denominator zero. We must exclude any xx that makes the original denominators in both f(x)f(x) and g(x)g(x) equal to zero.

  1. In f(x)=x6x+4f(x) = \frac{x - 6}{x + 4}, the denominator x+4=0x + 4 = 0, so x=4x = -4 is excluded.
  2. In g(x)=xx+4g(x) = \frac{x}{x + 4}, the denominator x+4=0x + 4 = 0, so again, x=4x = -4 is excluded.
  3. For fg(x)=x6x\frac{f}{g}(x) = \frac{x - 6}{x}, the denominator x=0x = 0 must be excluded as well.

Thus, the domain excludes both x=4x = -4 and x=0x = 0.

Final Domain:

The domain is all real numbers except x=4x = -4 and x=0x = 0. In interval notation, this is: (,4)(4,0)(0,)(-\infty, -4) \cup (-4, 0) \cup (0, \infty)

Final Answer:

fg(x)=x6x\frac{f}{g}(x) = \frac{x - 6}{x} Domain: (,4)(4,0)(0,)(-\infty, -4) \cup (-4, 0) \cup (0, \infty)

Would you like more details or have any questions?

Here are 5 related questions to explore:

  1. How do you handle division by zero when finding the domain of rational functions?
  2. What happens to the domain if the numerator has no variables?
  3. Can you give an example of a rational function with no restrictions on its domain?
  4. How do you find the domain of a composite function?
  5. How would the domain change if g(x)g(x) had a different denominator?

Tip: Always remember to check for restrictions from both the numerator and denominator when finding the domain of rational functions.

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Math Problem Analysis

Mathematical Concepts

Rational Functions
Division of Functions
Domain of a Function
Simplification

Formulas

f(x) / g(x) = [ (x - 6) / (x + 4) ] / [ x / (x + 4) ] = (x - 6) / x
Domain excludes x = -4 and x = 0

Theorems

Division of Rational Functions
Exclusion of values that make the denominator zero

Suitable Grade Level

Grades 10-12