Math Problem Statement

The function f is given by f(x) = 5x³-9x 4/x²-3x 2. At which of the following values of x does the graph of f have an x-intercept? A) x = 0 B) x = 3 C) x = 5 D) x = 1

Solution

To find the x-intercepts of a function, we need to set the function equal to zero and solve for xx. The x-intercept occurs when f(x)=0f(x) = 0.

You have the function:

f(x)=5x39x+4x23x+2f(x) = \frac{5x^3 - 9x + 4}{x^2 - 3x + 2}

Step 1: Set f(x)=0f(x) = 0

5x39x+4x23x+2=0\frac{5x^3 - 9x + 4}{x^2 - 3x + 2} = 0 For a fraction to be equal to zero, the numerator must be zero (since the denominator cannot be zero, as this would make the function undefined). So we only need to solve:

5x39x+4=05x^3 - 9x + 4 = 0

Step 2: Solve 5x39x+4=05x^3 - 9x + 4 = 0

To determine which of the given values of xx is a solution, we can substitute each into this equation.

  • For x=0x = 0: 5(0)39(0)+4=0+0+4=45(0)^3 - 9(0) + 4 = 0 + 0 + 4 = 4 So f(0)=4f(0) = 4, not zero. Thus, x=0x = 0 is not an x-intercept.

  • For x=3x = 3: 5(3)39(3)+4=5(27)27+4=13527+4=1125(3)^3 - 9(3) + 4 = 5(27) - 27 + 4 = 135 - 27 + 4 = 112 So f(3)=112f(3) = 112, not zero. Thus, x=3x = 3 is not an x-intercept.

  • For x=5x = 5: 5(5)39(5)+4=5(125)45+4=62545+4=5845(5)^3 - 9(5) + 4 = 5(125) - 45 + 4 = 625 - 45 + 4 = 584 So f(5)=584f(5) = 584, not zero. Thus, x=5x = 5 is not an x-intercept.

  • For x=1x = 1: 5(1)39(1)+4=5(1)9+4=59+4=05(1)^3 - 9(1) + 4 = 5(1) - 9 + 4 = 5 - 9 + 4 = 0 So f(1)=0f(1) = 0. Therefore, x=1x = 1 is an x-intercept.

Final Answer:

The graph of f(x)f(x) has an x-intercept at x=1\boxed{x = 1}.

Do you want further details on solving cubic equations or simplifying functions?

Here are 5 related questions to explore:

  1. What are the other intercepts of this function (y-intercept)?
  2. How can we determine the vertical asymptotes for rational functions?
  3. What is the process for factoring cubic equations like 5x39x+4=05x^3 - 9x + 4 = 0?
  4. How do you find critical points and analyze the graph of rational functions?
  5. What are the applications of x-intercepts in real-world scenarios?

Tip: When solving rational functions, focus on the numerator for x-intercepts and check for undefined points using the denominator.

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Math Problem Analysis

Mathematical Concepts

Algebra
Rational Functions
Cubic Equations

Formulas

f(x) = (5x³ - 9x + 4) / (x² - 3x + 2)
Setting f(x) = 0 to find x-intercepts

Theorems

X-intercept theorem
Factor theorem (for cubic equations)

Suitable Grade Level

Grades 10-12