Math Problem Statement

Find the domain and range of the following rational functions.

Solution

Let's solve the problems from the image. Each problem asks you to find the domain and range of a given rational function.

Independent Practice

  1. f(x)=2x+1f(x) = \frac{2}{x+1}

    • Domain: x1x \neq -1 (since x+1=0x + 1 = 0 when x=1x = -1)
    • Range: y0y \neq 0 (as 2x+1=0\frac{2}{x+1} = 0 has no solution)
  2. f(x)=3xx+3f(x) = \frac{3x}{x+3}

    • Domain: x3x \neq -3 (since x+3=0x + 3 = 0 when x=3x = -3)
    • Range: y3y \neq 3 (because the horizontal asymptote, as xx approaches infinity, is y=3y = 3)
  3. f(x)=3xx7f(x) = \frac{3-x}{x-7}

    • Domain: x7x \neq 7 (since x7=0x - 7 = 0 when x=7x = 7)
    • Range: y1y \neq -1 (since the function approaches -1 as xx increases)
  4. f(x)=2+xxf(x) = \frac{2+x}{x}

    • Domain: x0x \neq 0 (since the denominator cannot be zero)
    • Range: y1y \neq 1 (since the function 2+xx\frac{2+x}{x} simplifies to 1+2x1 + \frac{2}{x})
  5. f(x)=1x21f(x) = \frac{1}{x^2 - 1}

    • Domain: x1x \neq 1 and x1x \neq -1 (since x21=0x^2 - 1 = 0 at x=±1x = \pm 1)
    • Range: y>0y > 0 (since the function is always positive and cannot equal zero)

Independent Assessment

  1. f(x)=3x21f(x) = \frac{3}{x^2 - 1}

    • Domain: x1x \neq 1 and x1x \neq -1
    • Range: y>0y > 0
  2. f(x)=2xx4f(x) = \frac{2x}{x-4}

    • Domain: x4x \neq 4
    • Range: y2y \neq 2
  3. f(x)=x+35x5f(x) = \frac{x + 3}{5x - 5}

    • Domain: x1x \neq 1
    • Range: y25y \neq \frac{2}{5}
  4. f(x)=2+x2xf(x) = \frac{2+x}{2x}

    • Domain: x0x \neq 0
    • Range: y12y \neq \frac{1}{2}
  5. f(x)=x2+4x+3x29f(x) = \frac{x^2 + 4x + 3}{x^2 - 9}

    • Domain: x3x \neq 3 and x3x \neq -3
    • Range: y1y \neq 1

Would you like more details on any of these steps, or do you have any questions?

Relative Questions:

  1. What happens to the range of a rational function when the numerator is constant?
  2. How do you find vertical asymptotes of a rational function?
  3. Why does the function f(x)=2x+1f(x) = \frac{2}{x+1} never equal zero?
  4. What is the relationship between horizontal asymptotes and the range of a rational function?
  5. How can you determine the domain of a rational function by looking at its equation?

Tip:

When analyzing the range of a rational function, consider the function's behavior as xx approaches very large positive or negative values (horizontal asymptotes) and also check for values that make the numerator zero, as these can help identify values the function cannot take.

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Math Problem Analysis

Mathematical Concepts

Rational Functions
Domain
Range
Asymptotes

Formulas

Domain: Exclude values that make the denominator zero
Range: Horizontal asymptotes for large x values

Theorems

The Vertical Asymptote Theorem
Horizontal Asymptote Rules

Suitable Grade Level

Grades 10-12