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Local Behavior of Polynomial Functions
Learning Objectives
· Identify intercepts of polynomial functions in factored form
· Understand the relationship between degree, turning points, and x-intercepts
· Understand the intermediate value theorem
· Use factoring to find zeros of polynomial functions
· Identify zeros and their multiplicities from an equation or a graph
Identify intercepts of polynomial functions in factored form
1. Find the x- and y-intercepts of .
2. Find the x- and y-intercepts of .
3. Find the x- and y-intercepts of .
Interpreting Turning Points
A turning point is a point of the graph where the graph changes from increasing to decreasing (rising to falling) or decreasing to increasing (falling to rising).
A polynomial of degree n has n – 1 turning points.
Understand the relationship between degree, turning points, and x-intercepts
4. Find the maximum number of turning points of the following functions:
a.
b.
c.
Intermediate Value Theorem
Let be a polynomial function. The Intermediate Value Theorem states that if and have opposite signs, then there exists at least one value between and for which .
Understand the intermediate value theorem
5. Show that the function has a real zero between and
6. Show that the function has a real zero between and .
7. Show that the function has a real zero between and .
Use factoring to find zeros of polynomial functions
8. Find the x-intercepts of the following functions:
a.
b.
c.
Identify zeros and their multiplicities from an equation or a graph
9. Find all the zeros and their multiplicities for the function .
10. Find all the zeros and their multiplicities for the function .
11. Use the graph of the function of degree 4 below to find the zeros and their possible multiplicities.
ANSWER KEY
1.
2.
3.
4a. The function will have a maximum of 3 turning points.
4b. The function will have a maximum of 2 turning points.
4c. The function will have a maximum of 4 turning points.
5. . The sign change shows there is a zero between the given values.
6. . The sign change shows there is a zero between the given values.
7. . The sign change shows there is a zero between the given values.
8a.
8b.
8c.
9. have multiplicity of 1. has multiplicity 2.
10. has multiplicity 3, has multiplicity 2, has multiplicity 1.
11. . The graph touches the x-axis at both of the zeros so their multiplicity must be even and 2 since the degree of the function is 4.
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