Math Problem Statement

How many x-intercepts would the function f(x) = x(x - 2)^2(x^2 + 25)(x + 8)(x^2 - 5) have?

Solution

To determine how many x-intercepts the function f(x)=x(x2)2(x2+25)(x+8)(x25)f(x) = x(x - 2)^2(x^2 + 25)(x + 8)(x^2 - 5) has, we need to set f(x)=0f(x) = 0 and solve for xx. X-intercepts occur where the function equals zero, i.e., where the factors of the function are equal to zero.

The factors of f(x)f(x) are:

  1. xx
  2. (x2)2(x - 2)^2
  3. (x2+25)(x^2 + 25)
  4. (x+8)(x + 8)
  5. (x25)(x^2 - 5)

Let's solve for xx from each factor:

  1. From x=0x = 0: This gives one intercept at x=0x = 0.

  2. From (x2)2=0(x - 2)^2 = 0: Solving this, x=2x = 2. Since this factor is squared, x=2x = 2 is a repeated root, meaning it only counts as one intercept because it just touches the x-axis.

  3. From (x2+25)=0(x^2 + 25) = 0: Solving this: x2=25x^2 = -25 This has no real solutions (since you can't take the square root of a negative number), so it doesn't contribute any x-intercepts.

  4. From x+8=0x + 8 = 0: Solving this, x=8x = -8. This gives one intercept at x=8x = -8.

  5. From (x25)=0(x^2 - 5) = 0: Solving this: x2=5x=±5x^2 = 5 \quad \Rightarrow \quad x = \pm \sqrt{5} These are two real solutions, x=5x = \sqrt{5} and x=5x = -\sqrt{5}, giving two more intercepts.

Summary of x-intercepts:

  • x=0x = 0
  • x=2x = 2 (only one intercept due to the squared factor)
  • x=8x = -8
  • x=5x = \sqrt{5}
  • x=5x = -\sqrt{5}

Conclusion:

There are 5 x-intercepts in total.

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

Here are 5 related questions to expand on this topic:

  1. What is the significance of a double root for x-intercepts?
  2. How does the multiplicity of roots affect the shape of the graph?
  3. What is the geometric interpretation of complex roots for a polynomial function?
  4. How can you find the y-intercept of this function?
  5. How would adding another factor change the number of x-intercepts?

Tip: The degree of the polynomial gives insight into the number of possible real roots, but complex roots do not contribute to x-intercepts.

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Math Problem Analysis

Mathematical Concepts

Polynomial Functions
Factoring
Roots and Intercepts
Quadratic Equations

Formulas

Setting the polynomial equal to 0: f(x) = 0
Solving for roots: x^2 = -25 (no real solution), x^2 = 5 (real solutions x = ±√5)

Theorems

Fundamental Theorem of Algebra
Multiplicity of Roots

Suitable Grade Level

Grades 10-12