Math Problem Statement

Find the zeros for the polynomial function and give the multiplicity for each zero. State whether the graph crosses the x-axis or touches the x-axis and turns around at each zero. f(x) = -9(x+5)(x-8)^2

Solution

The polynomial function given is:

f(x)=9(x+5)(x8)2f(x) = -9(x+5)(x-8)^2

Step 1: Finding the Zeros

To find the zeros, set f(x)=0f(x) = 0:

9(x+5)(x8)2=0-9(x+5)(x-8)^2 = 0

This equation equals zero when either factor equals zero:

  1. x+5=0x=5x+5 = 0 \Rightarrow x = -5
  2. (x8)2=0x=8(x-8)^2 = 0 \Rightarrow x = 8

Thus, the zeros are x=5x = -5 and x=8x = 8.

Step 2: Multiplicity of Each Zero

  • The zero x=5x = -5 comes from the factor (x+5)(x + 5), which is raised to the first power. Therefore, its multiplicity is 1.
  • The zero x=8x = 8 comes from the factor (x8)2(x - 8)^2, which is squared. Therefore, its multiplicity is 2.

Step 3: Behavior of the Graph at Each Zero

  • At x=5x = -5: Since the multiplicity is 1 (odd), the graph crosses the x-axis at this point.
  • At x=8x = 8: Since the multiplicity is 2 (even), the graph touches the x-axis and turns around at this point.

Conclusion:

  • The zeros are x=5x = -5 and x=8x = 8.
  • Multiplicity of x=5x = -5 is 1, and the graph crosses the x-axis here.
  • Multiplicity of x=8x = 8 is 2, and the graph touches the x-axis and turns around here.

Would you like further details on any part of this?

Here are 5 related questions to expand on this:

  1. How does the leading coefficient of a polynomial affect the graph's end behavior?
  2. Can a polynomial have a zero with multiplicity greater than 2?
  3. What is the significance of the degree of a polynomial in relation to its zeros?
  4. How can you factor higher-degree polynomials to find their zeros?
  5. What happens to the graph of a polynomial if the multiplicity of a zero is 3?

Tip: The behavior at zeros can often be predicted by their multiplicity: odd multiplicities lead to crossings, while even multiplicities result in touching and turning.

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Math Problem Analysis

Mathematical Concepts

Polynomial Functions
Finding Zeros
Multiplicity
Graph Behavior at Zeros

Formulas

f(x) = 0 to find zeros
Factoring

Theorems

Factor Theorem
Multiplicity and Graph Behavior

Suitable Grade Level

Grades 9-11