Math Problem Statement

and find its domain and range.

IIL Given f(x) = (x - 5)/(x + 3) and g(x) = (x - 1)/x

Solution

Let's solve the problem step by step to find the domain and range for both functions:

1. Function f(x)=x5x+3f(x) = \frac{x - 5}{x + 3}

Domain of f(x)f(x):

The domain of a function consists of all the possible input values (x-values) that do not cause the function to be undefined. For rational functions, the function is undefined where the denominator is zero.

For f(x)=x5x+3f(x) = \frac{x - 5}{x + 3}, the denominator is x+3x + 3. Setting the denominator equal to zero:

x+3=0x=3x + 3 = 0 \quad \Rightarrow \quad x = -3

Thus, f(x)f(x) is undefined at x=3x = -3. Therefore, the domain of f(x)f(x) is all real numbers except x=3x = -3, or:

Domain of f(x):(,3)(3,)\text{Domain of } f(x): \quad (-\infty, -3) \cup (-3, \infty)

Range of f(x)f(x):

The range of a function is the set of all possible output values (y-values). To find the range of a rational function, it is useful to think about the behavior of the function as xx approaches certain values.

  1. As xx \to \infty or xx \to -\infty, the highest degree terms dominate, so the function approaches a horizontal asymptote. Here, the function simplifies to:

    x5x+3xx=1\frac{x - 5}{x + 3} \approx \frac{x}{x} = 1

    Therefore, the function has a horizontal asymptote at y=1y = 1.

  2. To check if the function can ever equal 1, set f(x)=1f(x) = 1:

    x5x+3=1x5=x+3\frac{x - 5}{x + 3} = 1 \quad \Rightarrow \quad x - 5 = x + 3

    Simplifying, we find this is a contradiction (no solution), so f(x)1f(x) \neq 1.

Thus, the range of f(x)f(x) is all real numbers except y=1y = 1:

Range of f(x):(,1)(1,)\text{Range of } f(x): \quad (-\infty, 1) \cup (1, \infty)


2. Function g(x)=x1xg(x) = \frac{x - 1}{x}

Domain of g(x)g(x):

For g(x)=x1xg(x) = \frac{x - 1}{x}, the denominator is xx. Setting the denominator equal to zero:

x=0x = 0

Thus, g(x)g(x) is undefined at x=0x = 0. Therefore, the domain of g(x)g(x) is all real numbers except x=0x = 0, or:

Domain of g(x):(,0)(0,)\text{Domain of } g(x): \quad (-\infty, 0) \cup (0, \infty)

Range of g(x)g(x):

Again, we analyze the function’s behavior:

  1. As xx \to \infty or xx \to -\infty, the highest degree terms dominate, so the function simplifies to:

    x1xxx=1\frac{x - 1}{x} \approx \frac{x}{x} = 1

    So, the function approaches a horizontal asymptote at y=1y = 1.

  2. To check if the function can equal 1, set g(x)=1g(x) = 1:

    x1x=1x1=x\frac{x - 1}{x} = 1 \quad \Rightarrow \quad x - 1 = x

    This is a contradiction, so g(x)1g(x) \neq 1.

Thus, the range of g(x)g(x) is all real numbers except y=1y = 1:

Range of g(x):(,1)(1,)\text{Range of } g(x): \quad (-\infty, 1) \cup (1, \infty)


Summary:

  • Domain of f(x)=x5x+3f(x) = \frac{x - 5}{x + 3}: (,3)(3,)(-\infty, -3) \cup (-3, \infty)
  • Range of f(x)f(x): (,1)(1,)(-\infty, 1) \cup (1, \infty)
  • Domain of g(x)=x1xg(x) = \frac{x - 1}{x}: (,0)(0,)(-\infty, 0) \cup (0, \infty)
  • Range of g(x)g(x): (,1)(1,)(-\infty, 1) \cup (1, \infty)

Would you like to go into further detail on any part of this? Let me know!

Here are 5 related questions to explore this further:

  1. How do vertical asymptotes affect the domain of a rational function?
  2. Why can't rational functions reach their horizontal asymptotes?
  3. Can you find the x-intercept and y-intercept of f(x)f(x) and g(x)g(x)?
  4. How do you find slant asymptotes for more complex rational functions?
  5. What happens to the range of a function if you modify its numerator or denominator?

Tip: Always check for points where the denominator is zero to ensure the function remains defined when determining the domain of rational functions!

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Math Problem Analysis

Mathematical Concepts

Rational Functions
Domain and Range
Asymptotes

Formulas

Domain of rational function: Denominator ≠ 0
Range of rational function: Asymptotic behavior

Theorems

Horizontal Asymptote Theorem
Vertical Asymptote Theorem

Suitable Grade Level

Grades 10-12