# Describing End Behavior of Polynomial Functions

HA2 5.1 Polynomial Basics
Objectives:
To classify polynomials
To graph polynomial functions
To describe the end behavior
Polynomial functions have distinguishing “behaviors.” Looking at
its algebraic form tells a lot about its graph and vise-versa. Using algebraic and graphical analysis, one can
determine the degree and basic shape.
ESSENTIAL UNDERSTANDING:
KEY TERMS_:
__
_____
Monomial
Polynomial
Degree
Polynomial Function
Turning Point
End Behavior
You can classify a polynomial by its degree or by its number of terms.
 These vocabulary words must be used correctly to describe a polynomial expression.
Name Using
Degree
Polynomial
Example
Number of
Terms
0
5
1
1
x4
2
2
4x 2
1
3
4x 3  3x 2  x
3
4
2x 4  5x 2
2
5
x 5  4x 2  2x  1
4
Degree
Example
Name Using
Number of Terms
polynomial of 4 terms
Classifying Polynomials
Write –3x + 4x + 7x – 3 in standard form. What is the classification of this polynomial by its degree? by its
number of terms?
3
Got It?
Write each polynomial in standard form. What is the classification of each by degree? by number of terms?
a. 3x 3  x  5x 4
b. 3 4x 5  2x 2  10
Exploration Activity of Polynomial End Behaviors
Example
Describing End Behavior of Polynomial Functions
Consider the leading term of y = 3x4 – 2x3 + x – 1. What is the end behavior of the graph?
Got It?
Consider the leading term of y  4x 3  2x 2  7 . What is the end behavior of the graph?
.
You can determine the end behavior of a
polynomial function of degree n from the
leading term axn of the standard form.
Look at the polynomials above. What do
you think is meant by the phrases “up and
up,” “down and down,” “down and up,”
and “up and down?”
How can you use the leading term of the polynomial to determine the end behavior?
Why do you think that the end behavior of a polynomial function does not rely on any other term than the
You can tell, by the degree of the leading coefficient, the maximum number of turning points of a
polynomial.
Look at the shapes of the following polynomials. Then use a graphing calculator to look at polynomials
of different degrees. Describe a pattern you notice about the number of turning points and the degree of the
polynomial.
 If the graph of a polynomial function has “t” turning points, how can you describe its degree?
Example
Graphing Cubic Functions
What is the graph of y = 3 – 2x3 + x? Describe the graph.
x
-2
-1
0
1
2
y
Got It?
What is the graph of each cubic function? Describe the graph.
a. y  x 3  2x 2  x  2
b. y  x 3  1
Before you start these problems, think: what should the end behaviors be?
x
-2
-1
0
1
2
y
x
-2
-1
0
1
2
y
Suppose you are given a set of polynomial function ordered pairs. When the inputs (x-values) of the polynomial
differ by a constant, it is possible to analyze the differences of consecutive outputs (y-values) to determine the leastdegree polynomial function that could generate the data.
Example
Using Finite Differences to Determine Degree
What is the degree of the polynomial function that generates the data shown in the table?
Got It?
What is the degree of the polynomial function that generates the data shown at the right?
Reasoning What is an example of a polynomial function whose fifth differences are
constant but whose fourth differences are not constant?
Homework:
Pg 285: #1-7, 21-39 odd, 40-56
Exit Slip Questions
Answer these questions on this slip of paper, then remove from your packet and give to your teacher before
you leave the room.
Name: _______________________________
Per: 4
December 5, 2012
1. Wrtie 2x 3  3x 2  x 5 in standard form. What is the classification of this polynomial by its degree?
By its number of terms?
2. Consider the leading term of y  2x 2  3x  3 . What is the end behavior of the graph? Include a