Math Problem Statement

Write an equation for a rational function with:

Vertical asymptotes at x = 5 and x = -2

x-intercepts at x = -5 and x = -3

y-intercept at 7

Solution

To construct a rational function with the given characteristics, we'll proceed step by step:

1. Vertical Asymptotes at x=5x = 5 and x=2x = -2:

Vertical asymptotes occur when the denominator of a rational function equals zero. Therefore, the denominator must include the factors (x5)(x - 5) and (x+2)(x + 2), since the function will be undefined at these points.

Thus, the denominator will be: (x5)(x+2)(x - 5)(x + 2)

2. x-Intercepts at x=5x = -5 and x=3x = -3:

x-intercepts occur when the numerator of a rational function equals zero. To achieve intercepts at x=5x = -5 and x=3x = -3, the numerator must include the factors (x+5)(x + 5) and (x+3)(x + 3), as these will result in zero when x=5x = -5 and x=3x = -3.

Thus, the numerator will be: (x+5)(x+3)(x + 5)(x + 3)

3. y-Intercept at y=7y = 7:

The y-intercept occurs when x=0x = 0. To ensure that the function passes through the point (0,7)(0, 7), we need to scale the rational function by a constant AA. To find AA, we substitute x=0x = 0 into the equation and set the output to 7.

The function (with the constant AA) so far is: f(x)=A(x+5)(x+3)(x5)(x+2)f(x) = A \frac{(x + 5)(x + 3)}{(x - 5)(x + 2)}

Substitute x=0x = 0 into the equation: f(0)=A(0+5)(0+3)(05)(0+2)=A5352=A1510=32Af(0) = A \frac{(0 + 5)(0 + 3)}{(0 - 5)(0 + 2)} = A \frac{5 \cdot 3}{-5 \cdot 2} = A \frac{15}{-10} = -\frac{3}{2}A Since the y-intercept is 7, we set f(0)=7f(0) = 7: 32A=7-\frac{3}{2}A = 7 Solve for AA: A=143A = -\frac{14}{3}

4. Final Equation:

Now that we know the constant A=143A = -\frac{14}{3}, the equation of the rational function is: f(x)=143(x+5)(x+3)(x5)(x+2)f(x) = -\frac{14}{3} \frac{(x + 5)(x + 3)}{(x - 5)(x + 2)}

This is the rational function that satisfies all the given conditions.


Would you like further details on this, or do you have any questions?

Here are 5 related questions for further exploration:

  1. How does changing the constant AA affect the graph of the rational function?
  2. How would the function change if the y-intercept were different?
  3. What happens if a rational function has no vertical asymptotes?
  4. How do you find horizontal asymptotes of a rational function?
  5. What is the significance of a hole in the graph of a rational function?

Tip: Always verify the behavior at intercepts and asymptotes when constructing or analyzing rational functions.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Rational Functions
Asymptotes
Intercepts

Formulas

Vertical asymptotes: Denominator factors (x - 5)(x + 2)
x-intercepts: Numerator factors (x + 5)(x + 3)
y-intercept: Scaling factor A

Theorems

Rational Function Behavior
Asymptote Definition
Intercepts in Rational Functions

Suitable Grade Level

Grades 10-12