2. Writing a Polynomial in Factored
Form
In Chapter 4, we solved quadratic
functions by factoring and setting each
factor equal to zero
We can solve some polynomial
functions in a similar way.
◦ Remember: ALWAYS factor out the GCF
first!
3. Linear Factors, Roots, Zeros,
and x-intercepts
The following are equivalent
statements about a real number b and
a polynomial P(x)
◦ (x – b) is a linear factor of the polynomial
P(x)
◦ b is a zero of the polynomial function y =
P(x)
◦ b is a root (or solution) of the polynomial
equation P(x) = 0
◦ b is an x-intercept of the graph of y =
P(x)
4. Example: Write each polynomial
in factored form. Then, find the
zeros of the function.
5. Example: Write each polynomial
in factored form. Then, find the
zeros of the function.
6. Graphing a Polynomial
Function
1. Find the zeros and plot them
2. Find points between the zeros and
plot them
3. Determine the end behavior
4. Sketch the graph
9. The Factor Theorem
The factor theorem describes the
relationship between the linear factors
of a polynomial and the zeros of a
polynomial.
The Factor Theorem
The expression x – a is a factor of a
polynomial if and only if the value a is
a zero of the related polynomial
function
10. Using the Factor Theorem to
Write a Polynomial
1. Write each zero as a factor
2. Multiply and combine like terms
11. Example: Write a polynomial
function in standard form with the
given zeros
X = –2, 2, and 3
12. Example: Write a polynomial
function in standard form with the
given zeros
X = –2, –2, 2 and 3
14. Multiple Zeros and Multiplicity
A multiple zero is a linear factor that
is repeated when the polynomial is
factored completely
The multiplicity of a zero is the
number of times the linear factor is
repeated in the factored form of the
polynomial.
◦ If a zero is of even multiplicity, then the
graph touches the x-axis and “turns
around”
◦ If a zero is of odd multiplicity, then the
graph crosses the x-axis
15. Example: Find the zeros of the
function. State the multiplicity of
multiple zeros.
What does the
multiplicity tell
you about the
graph?