Add and Subtract Polynomials

6.1 Add and Subtract Polynomials

Learning Objectives

By the end of this section, you will be able to:

Identify polynomials, monomials, binomials, and trinomials
Determine the degree of polynomials
Add and subtract monomials
Add and subtract polynomials
Evaluate a polynomial for a given value

Be Prepared 6.1

Before you get started, take this readiness quiz.

Simplify: $8 x + 3 x .$
If you missed this problem, review Example 1.24.

Be Prepared 6.2

Subtract: $(5 n + 8) - (2 n - 1) .$
If you missed this problem, review Example 1.139.

Be Prepared 6.3

Write in expanded form: $a^{5} .$
If you missed this problem, review Example 1.14.

Identify Polynomials, Monomials, Binomials and Trinomials

You have learned that a term is a constant or the product of a constant and one or more variables. The constant is called a coefficient. When it is of the form $a x^{m}$ , where $a$ is a constant and $m$ is a whole number, it is called a monomial. Some examples of monomial are $8, −2 x^{2}, 4 y^{3}, and 11 z^{7}$ .

Monomials

A monomial is a term of the form $a x^{m}$ , where $a$ is a constant and $m$ is a positive whole number.

A monomial, or two or more monomials combined by addition or subtraction, is a polynomial. Some polynomials have special names, based on the number of terms. A monomial is a polynomial with exactly one term. A binomial has exactly two terms, and a trinomial has exactly three terms. There are no special names for polynomials with more than three terms.

Polynomials

polynomial—A monomial, or two or more monomials combined by addition or subtraction, is a polynomial.

monomial—A polynomial with exactly one term is called a monomial.
binomial—A polynomial with exactly two terms is called a binomial.
trinomial—A polynomial with exactly three terms is called a trinomial.

Here are some examples of polynomials.

$\begin{matrix} Polynomial & b + 1 & 4 y^{2} - 7 y + 2 & 4 x^{4} + x^{3} + 8 x^{2} - 9 x + 1 \\ Monomial & 14 & 8 y^{2} & −9 x^{3} y^{5} & −13 \\ Binomial & a + 7 & 4 b - 5 & y^{2} - 16 & 3 x^{3} - 9 x^{2} \\ Trinomial & x^{2} - 7 x + 12 & 9 y^{2} + 2 y - 8 & 6 m^{4} - m^{3} + 8 m & z^{4} + 3 z^{2} - 1 \end{matrix}$

Notice that every monomial, binomial, and trinomial is also a polynomial. They are just special members of the “family” of polynomials and so they have special names. We use the words monomial, binomial, and trinomial when referring to these special polynomials and just call all the rest polynomials.

Example 6.1

Determine whether each polynomial is a monomial, binomial, trinomial, or other polynomial.

ⓐ $4 y^{2} - 8 y - 6$
ⓑ $−5 a^{4} b^{2}$
ⓒ $2 x^{5} - 5 x^{3} - 9 x^{2} + 3 x + 4$
ⓓ $13 - 5 m^{3}$
ⓔ $q$

Solution

	Polynomial	Number of terms	Type
ⓐ	$4 y^{2} - 8 y - 6$	$3$	Trinomial
ⓑ	$−5 a^{4} b^{2}$	$1$	Monomial
ⓒ	$2 x^{5} - 5 x^{3} - 9 x^{2} + 3 x + 4$	$5$	Polynomial
ⓓ	$13 - 5 m^{3}$	$2$	Binomial
ⓔ	$q$	$1$	Monomial

Examples of polynomials, showing their number of terms and classification type.

Try It 6.1

Determine whether each polynomial is a monomial, binomial, trinomial, or other polynomial:

ⓐ $5 b$ ⓑ $8 y^{3} - 7 y^{2} - y - 3$ ⓒ $−3 x^{2} - 5 x + 9$ ⓓ $81 - 4 a^{2}$ ⓔ $−5 x^{6}$

Try It 6.2

Determine whether each polynomial is a monomial, binomial, trinomial, or other polynomial:

ⓐ $27 z^{3} - 8$ ⓑ $12 m^{3} - 5 m^{2} - 2 m$ ⓒ $\frac{5}{6}$ ⓓ $8 x^{4} - 7 x^{2} - 6 x - 5$ ⓔ $− n^{4}$

Determine the Degree of Polynomials

The degree of a polynomial and the degree of its terms are determined by the exponents of the variable.

A monomial that has no variable, just a constant, is a special case. The degree of a constant is 0—it has no variable.

Degree of a Polynomial

The degree of a term is the sum of the exponents of its variables.

The degree of a constant is 0.

The degree of a polynomial is the highest degree of all its terms.

Let’s see how this works by looking at several polynomials. We’ll take it step by step, starting with monomials, and then progressing to polynomials with more terms.

This table has 11 rows and 5 columns. The first column is a header column, and it names each row. The first row is named “Monomial,” and each cell in this row contains a different monomial. The second row is named “Degree,” and each cell in this row contains the degree of the monomial above it. The degree of 14 is 0, the degree of 8y squared is 2, the degree of negative 9x cubed y to the fifth power is 8, and the degree of negative 13a is 1. The third row is named “Binomial,” and each cell in this row contains a different binomial. The fourth row is named “Degree of each term,” and each cell contains the degrees of the two terms in the binomial above it. The fifth row is named “Degree of polynomial,” and each cell contains the degree of the binomial as a whole.” The degrees of the terms in a plus 7 are 0 and 1, and the degree of the whole binomial is 1. The degrees of the terms in 4b squared minus 5b are 2 and 1, and the degree of the whole binomial is 2. The degrees of the terms in x squared y squared minus 16 are 4 and 0, and the degree of the whole binomial is 4. The degrees of the terms in 3n cubed minus 9n squared are 3 and 2, and the degree of the whole binomial is 3. The sixth row is named “Trinomial,” and each cell in this row contains a different trinomial. The seventh row is named “Degree of each term,” and each cell contains the degrees of the three terms in the trinomial above it. The eighth row is named “Degree of polynomial,” and each cell contains the degree of the trinomial as a whole. The degrees of the terms in x squared minus 7x plus 12 are 2, 1, and 0, and the degree of the whole trinomial is 2. The degrees of the terms in 9a squared plus 6ab plus b squared are 2, 2, and 2, and the degree of the trinomial as a whole is 2. The degrees of the terms in 6m to the fourth power minus m cubed n squared plus 8mn to the fifth power are 4, 5, and 6, and the degree of the whole trinomial is 6. The degrees of the terms in z to the fourth power plus 3z squared minus 1 are 4, 2, and 0, and the degree of the whole trinomial is 4. The ninth row is named “Polynomial,” and each cell contains a different polynomial. The tenth row is named “Degree of each term,” and the eleventh row is named “Degree of polynomial.” The degrees of the terms in b plus 1 are 1 and 0, and the degree of the whole polynomial is 1. The degrees of the terms in 4y squared minus 7y plus 2 are 2, 1, and 0, and the degree of the whole polynomial is 2. The degrees of the terms in 4x to the fourth power plus x cubed plus 8x squared minus 9x plus 1 are 4, 3, 2, 1, and 0, and the degree of the whole polynomial is 4.

A polynomial is in standard form when the terms of a polynomial are written in descending order of degrees. Get in the habit of writing the term with the highest degree first.

Example 6.2

Find the degree of the following polynomials.

ⓐ $10 y$
ⓑ $4 x^{3} - 7 x + 5$
ⓒ $−15$
ⓓ $−8 b^{2} + 9 b - 2$
ⓔ $8 x y^{2} + 2 y$

Solution

ⓐ The exponent of $y$ is one. $y = y^{1}$	$10 y$ The degree is 1.
ⓑ The highest degree of all the terms is 3.	$4 x^{3} - 7 x + 5$ The degree is 3.
ⓒ The degree of a constant is 0.	$−15$ The degree is 0.
ⓓ The highest degree of all the terms is 2.	$−8 b^{2} + 9 b - 2$ The degree is 2.
ⓔ The highest degree of all the terms is 3.	$8 x y^{2} + 2 y$ The degree is 3.

This table demonstrates how to determine the degree of various mathematical expressions, including monomials, polynomials, and constants.

Try It 6.3

Find the degree of the following polynomials:

ⓐ $−15 b$ ⓑ $10 z^{4} + 4 z^{2} - 5$ ⓒ $12 c^{5} d^{4} + 9 c^{3} d^{9} - 7$ ⓓ $3 x^{2} y - 4 x$ ⓔ $−9$

Try It 6.4

Find the degree of the following polynomials:

ⓐ $52$ ⓑ $a^{4} b - 17 a^{4}$ ⓒ $5 x + 6 y + 2 z$ ⓓ $3 x^{2} - 5 x + 7$ ⓔ $− a^{3}$

Add and Subtract Monomials

You have learned how to simplify expressions by combining like terms. Remember, like terms must have the same variables with the same exponent. Since monomials are terms, adding and subtracting monomials is the same as combining like terms. If the monomials are like terms, we just combine them by adding or subtracting the coefficient.

Example 6.3

Add: $25 y^{2} + 15 y^{2}$ .

Solution

	$25 y^{2} + 15 y^{2}$
Combine like terms.	$40 y^{2}$

This table demonstrates the process of combining like terms in an algebraic expression.

Try It 6.5

Add: $12 q^{2} + 9 q^{2} .$

Try It 6.6

Add: $−15 c^{2} + 8 c^{2} .$

Example 6.4

Subtract: $16 p - (−7 p)$ .

Solution

	$16 p - (−7 p)$
Combine like terms.	$23 p$

This table demonstrates the step-by-step simplification of an algebraic expression by combining like terms.

Try It 6.7

Subtract: $8 m - (−5 m) .$

Try It 6.8

Subtract: $−15 z^{3} - (−5 z^{3}) .$

Remember that like terms must have the same variables with the same exponents.

Example 6.5

Simplify: $c^{2} + 7 d^{2} - 6 c^{2}$ .

Solution

	$c^{2} + 7 d^{2} - 6 c^{2}$
Combine like terms.	$−5 c^{2} + 7 d^{2}$

Demonstrates simplifying an algebraic expression by combining like terms.

Try It 6.9

Add: $8 y^{2} + 3 z^{2} - 3 y^{2} .$

Try It 6.10

Add: $3 m^{2} + n^{2} - 7 m^{2} .$

Example 6.6

Simplify: $u^{2} v + 5 u^{2} - 3 v^{2}$ .

Solution

	$u^{2} v + 5 u^{2} - 3 v^{2}$
There are no like terms to combine.	$u^{2} v + 5 u^{2} - 3 v^{2}$

An algebraic expression and a note on its like terms.

Try It 6.11

Simplify: $m^{2} n^{2} - 8 m^{2} + 4 n^{2} .$

Try It 6.12

Simplify: $p q^{2} - 6 p - 5 q^{2} .$

We can think of adding and subtracting polynomials as just adding and subtracting a series of monomials. Look for the like terms—those with the same variables and the same exponent. The Commutative Property allows us to rearrange the terms to put like terms together.

Example 6.7

Find the sum: $(5 y^{2} - 3 y + 15) + (3 y^{2} - 4 y - 11) .$

Solution

Identify like terms.
Rearrange to get the like terms together.
Combine like terms.

Try It 6.13

Find the sum: $(7 x^{2} - 4 x + 5) + (x^{2} - 7 x + 3) .$

Try It 6.14

Find the sum: $(14 y^{2} + 6 y - 4) + (3 y^{2} + 8 y + 5) .$

Example 6.8

Find the difference: $(9 w^{2} - 7 w + 5) - (2 w^{2} - 4) .$

Solution


Distribute and identify like terms.
Rearrange the terms.
Combine like terms.

Try It 6.15

Find the difference: $(8 x^{2} + 3 x - 19) - (7 x^{2} - 14) .$

Try It 6.16

Find the difference: $(9 b^{2} - 5 b - 4) - (3 b^{2} - 5 b - 7) .$

Example 6.9

Subtract: $(c^{2} - 4 c + 7)$ from $(7 c^{2} - 5 c + 3)$ .

Solution



Distribute and identify like terms.
Rearrange the terms.
Combine like terms.

Try It 6.17

Subtract: $(5 z^{2} - 6 z - 2)$ from $(7 z^{2} + 6 z - 4)$ .

Try It 6.18

Subtract: $(x^{2} - 5 x - 8)$ from $(6 x^{2} + 9 x - 1)$ .

Example 6.10

Find the sum: $(u^{2} - 6 u v + 5 v^{2}) + (3 u^{2} + 2 u v)$ .

Solution

	$(u^{2} - 6 u v + 5 v^{2}) + (3 u^{2} + 2 u v)$
Distribute.	$u^{2} - 6 u v + 5 v^{2} + 3 u^{2} + 2 u v$
Rearrange the terms, to put like terms together.	$u^{2} + 3 u^{2} - 6 u v + 2 u v + 5 v^{2}$
Combine like terms.	$4 u^{2} - 4 u v + 5 v^{2}$

Step-by-step addition of two polynomial expressions, showing distribution, rearrangement, and combining like terms for simplification.

Try It 6.19

Find the sum: $(3 x^{2} - 4 x y + 5 y^{2}) + (2 x^{2} - x y)$ .

Try It 6.20

Find the sum: $(2 x^{2} - 3 x y - 2 y^{2}) + (5 x^{2} - 3 x y)$ .

Example 6.11

Find the difference: $(p^{2} + q^{2}) - (p^{2} + 10 p q - 2 q^{2})$ .

Solution

	$(p^{2} + q^{2}) - (p^{2} + 10 p q - 2 q^{2})$
Distribute.	$p^{2} + q^{2} - p^{2} - 10 p q + 2 q^{2}$
Rearrange the terms, to put like terms together.	$p^{2} - p^{2} - 10 p q + q^{2} + 2 q^{2}$
Combine like terms.	$−10 p q + 3 q^{2}$

Step-by-step algebraic simplification of the expression (p^2 + q^2) - (p^2 + 10pq - 2q^2).

Try It 6.21

Find the difference: $(a^{2} + b^{2}) - (a^{2} + 5 a b - 6 b^{2})$ .

Try It 6.22

Find the difference: $(m^{2} + n^{2}) - (m^{2} - 7 m n - 3 n^{2})$ .

Example 6.12

Simplify: $(a^{3} - a^{2} b) - (a b^{2} + b^{3}) + (a^{2} b + a b^{2})$ .

Solution

	$(a^{3} - a^{2} b) - (a b^{2} + b^{3}) + (a^{2} b + a b^{2})$
Distribute.	$a^{3} - a^{2} b - a b^{2} - b^{3} + a^{2} b + a b^{2}$
Rearrange the terms, to put like terms together.	$a^{3} - a^{2} b + a^{2} b - a b^{2} + a b^{2} - b^{3}$
Combine like terms.	$a^{3} - b^{3}$

Step-by-step simplification of an algebraic expression through distribution, rearrangement, and combining like terms.

Try It 6.23

Simplify: $(x^{3} - x^{2} y) - (x y^{2} + y^{3}) + (x^{2} y + x y^{2})$ .

Try It 6.24

Simplify: $(p^{3} - p^{2} q) + (p q^{2} + q^{3}) - (p^{2} q + p q^{2})$ .

Evaluate a Polynomial for a Given Value

We have already learned how to evaluate expressions. Since polynomials are expressions, we’ll follow the same procedures to evaluate a polynomial. We will substitute the given value for the variable and then simplify using the order of operations.

Example 6.13

Evaluate $5 x^{2} - 8 x + 4$ when

ⓐ $x = 4$
ⓑ $x = −2$
ⓒ $x = 0$

Solution

ⓐ $x = 4$


Simplify the exponents.
Multiply.
Simplify.

ⓑ $x = −2$


Simplify the exponents.
Multiply.
Simplify.

ⓒ $x = 0$


Simplify the exponents.
Multiply.
Simplify.

Try It 6.25

Evaluate: $3 x^{2} + 2 x - 15$ when

ⓐ $x = 3$
ⓑ $x = −5$
ⓒ $x = 0$

Try It 6.26

Evaluate: $5 z^{2} - z - 4$ when

ⓐ $z = −2$
ⓑ $z = 0$
ⓒ $z = 2$

Example 6.14

The polynomial $−16 t^{2} + 250$ gives the height of a ball $t$ seconds after it is dropped from a 250 foot tall building. Find the height after $t = 2$ seconds.

Solution

	$−16 t^{2} + 250$
Substitute $t = 2$ .	$−16 {(2)}^{2} + 250$
Simplify.	$−16 \cdot 4 + 250$
Simplify.	$−64 + 250$
Simplify.	$186$
	After 2 seconds the height of the ball is 186 feet.

Step-by-step evaluation of the expression -16t^2 + 250 at t=2, determining the height of a ball.

Try It 6.27

The polynomial $−16 t^{2} + 250$ gives the height of a ball $t$ seconds after it is dropped from a 250-foot tall building. Find the height after $t = 0$ seconds.

Try It 6.28

The polynomial $−16 t^{2} + 250$ gives the height of a ball $t$ seconds after it is dropped from a 250-foot tall building. Find the height after $t = 3$ seconds.

Example 6.15

The polynomial $6 x^{2} + 15 x y$ gives the cost, in dollars, of producing a rectangular container whose top and bottom are squares with side x feet and sides of height y feet. Find the cost of producing a box with $x = 4$ feet and $y = 6$ feet.

Solution



Simplify.
Simplify.
Simplify.
	The cost of producing the box is $456.

Try It 6.29

Try It 6.30

Media

Access these online resources for additional instruction and practice with adding and subtracting polynomials.

Section 6.1 Exercises

Practice Makes Perfect

Identify Polynomials, Monomials, Binomials, and Trinomials

In the following exercises, determine if each of the following polynomials is a monomial, binomial, trinomial, or other polynomial.

ⓐ $81 b^{5} - 24 b^{3} + 1$ ⓑ $5 c^{3} + 11 c^{2} - c - 8$ ⓒ $\frac{14}{15} y + \frac{1}{7}$
ⓓ 5
ⓔ $4 y + 17$

ⓐ $x^{2} - y^{2}$ ⓑ $−13 c^{4}$ ⓒ $x^{2} + 5 x - 7$ ⓓ $x^{2} y^{2} - 2 x y + 8$ ⓔ 19

ⓐ $8 - 3 x$ ⓑ $z^{2} - 5 z - 6$ ⓒ $y^{3} - 8 y^{2} + 2 y - 16$ ⓓ $81 b^{5} - 24 b^{3} + 1$ ⓔ $−18$

ⓐ $11 y^{2}$ ⓑ $−73$ ⓒ $6 x^{2} - 3 x y + 4 x - 2 y + y^{2}$ ⓓ $4 y + 17$ ⓔ $5 c^{3} + 11 c^{2} - c - 8$

Determine the Degree of Polynomials

In the following exercises, determine the degree of each polynomial.

ⓐ $6 a^{2} + 12 a + 14$ ⓑ $18 x y^{2} z$ ⓒ $5 x + 2$ ⓓ $y^{3} - 8 y^{2} + 2 y - 16$ ⓔ $−24$

ⓐ $9 y^{3} - 10 y^{2} + 2 y - 6$ ⓑ $−12 p^{4}$ ⓒ $a^{2} + 9 a + 18$ ⓓ $20 x^{2} y^{2} - 10 a^{2} b^{2} + 30$ ⓔ 17

ⓐ $14 - 29 x$ ⓑ $z^{2} - 5 z - 6$ ⓒ $y^{3} - 8 y^{2} + 2 y - 16$ ⓓ $23 a b^{2} - 14$ ⓔ $−3$

ⓐ $62 y^{2}$ ⓑ 15 ⓒ $6 x^{2} - 3 x y + 4 x - 2 y + y^{2}$ ⓓ $10 - 9 x$ ⓔ $m^{4} + 4 m^{3} + 6 m^{2} + 4 m + 1$

Add and Subtract Monomials

In the following exercises, add or subtract the monomials.

${7x}^{2} + 5 x^{2}$

10.

${4y}^{3} + 6 y^{3}$

11.

$−12 w + 18 w$

12.

$−3 m + 9 m$

13.

$4a - 9 a$

14.

$− y - 5 y$

15.

$28 x - (−12 x)$

16.

$13 z - (−4 z)$

17.

$−5 b - 17 b$

18.

$−10 x - 35 x$

19.

$12 a + 5 b - 22 a$

20.

$14x - 3 y - 13 x$

21.

$2 a^{2} + b^{2} - 6 a^{2}$

22.

$5 u^{2} + 4 v^{2} - 6 u^{2}$

23.

$x y^{2} - 5 x - 5 y^{2}$

24.

$p q^{2} - 4 p - 3 q^{2}$

25.

$a^{2} b - 4 a - 5 a b^{2}$

26.

$x^{2} y - 3 x + 7 x y^{2}$

27.

$12a + 8 b$

28.

$19y + 5 z$

29.

Add: $4 a, −3 b, −8 a$

30.

Add: $4x, 3 y, −3 x$

31.

Subtract $5 x^{6} from - 12 x^{6}$ .

32.

Subtract $2 p^{4} from - 7 p^{4}$ .

Add and Subtract Polynomials

In the following exercises, add or subtract the polynomials.

33.

$(5 y^{2} + 12 y + 4) + (6 y^{2} - 8 y + 7)$

34.

$(4 y^{2} + 10 y + 3) + (8 y^{2} - 6 y + 5)$

35.

$(x^{2} + 6 x + 8) + (−4 x^{2} + 11 x - 9)$

36.

$(y^{2} + 9 y + 4) + (−2 y^{2} - 5 y - 1)$

37.

$(8 x^{2} - 5 x + 2) + (3 x^{2} + 3)$

38.

$(7 x^{2} - 9 x + 2) + (6 x^{2} - 4)$

39.

$(5 a^{2} + 8) + (a^{2} - 4 a - 9)$

40.

$(p^{2} - 6 p - 18) + (2 p^{2} + 11)$

41.

$(4 m^{2} - 6 m - 3) - (2 m^{2} + m - 7)$

42.

$(3 b^{2} - 4 b + 1) - (5 b^{2} - b - 2)$

43.

$(a^{2} + 8 a + 5) - (a^{2} - 3 a + 2)$

44.

$(b^{2} - 7 b + 5) - (b^{2} - 2 b + 9)$

45.

$(12 s^{2} - 15 s) - (s - 9)$

46.

$(10 r^{2} - 20 r) - (r - 8)$

47.

Subtract $(9 x^{2} + 2)$ from $(12 x^{2} - x + 6)$ .

48.

Subtract $(5 y^{2} - y + 12)$ from $(10 y^{2} - 8 y - 20)$ .

49.

Subtract $(7 w^{2} - 4 w + 2)$ from $(8 w^{2} - w + 6)$ .

50.

Subtract $(5 x^{2} - x + 12)$ from $(9 x^{2} - 6 x - 20)$ .

51.

Find the sum of $(2 p^{3} - 8)$ and $(p^{2} + 9 p + 18)$ .

52.

Find the sum of
$(q^{2} + 4 q + 13)$ and $(7 q^{3} - 3)$ .

53.

Find the sum of $(8 a^{3} - 8 a)$ and $(a^{2} + 6 a + 12)$ .

54.

Find the sum of
$(b^{2} + 5 b + 13)$ and $(4 b^{3} - 6)$ .

55.

Find the difference of
$(w^{2} + w - 42)$ and
$(w^{2} - 10 w + 24)$ .

56.

Find the difference of
$(z^{2} - 3 z - 18)$ and
$(z^{2} + 5 z - 20)$ .

57.

Find the difference of
$(c^{2} + 4 c - 33)$ and
$(c^{2} - 8 c + 12)$ .

58.

Find the difference of
$(t^{2} - 5 t - 15)$ and
$(t^{2} + 4 t - 17)$ .

59.

$(7 x^{2} - 2 x y + 6 y^{2}) + (3 x^{2} - 5 x y)$

60.

$(−5 x^{2} - 4 x y - 3 y^{2}) + (2 x^{2} - 7 x y)$

61.

$(7 m^{2} + m n - 8 n^{2}) + (3 m^{2} + 2 m n)$

62.

$(2 r^{2} - 3 r s - 2 s^{2}) + (5 r^{2} - 3 r s)$

63.

$(a^{2} - b^{2}) - (a^{2} + 3 a b - 4 b^{2})$

64.

$(m^{2} + 2 n^{2}) - (m^{2} - 8 m n - n^{2})$

65.

$(u^{2} - v^{2}) - (u^{2} - 4 u v - 3 v^{2})$

66.

$(j^{2} - k^{2}) - (j^{2} - 8 j k - 5 k^{2})$

67.

$(p^{3} - 3 p^{2} q) + (2 p q^{2} + 4 q^{3}) - (3 p^{2} q + p q^{2})$

68.

$(a^{3} - 2 a^{2} b) + (a b^{2} + b^{3}) - (3 a^{2} b + 4 a b^{2})$

69.

$(x^{3} - x^{2} y) - (4 x y^{2} - y^{3}) + (3 x^{2} y - x y^{2})$

70.

$(x^{3} - 2 x^{2} y) - (x y^{2} - 3 y^{3}) - (x^{2} y - 4 x y^{2})$

Evaluate a Polynomial for a Given Value

In the following exercises, evaluate each polynomial for the given value.

71.

Evaluate $8 y^{2} - 3 y + 2$ when:

72.

Evaluate $5 y^{2} - y - 7$ when:

73.

Evaluate $4 - 36 x$ when:

74.

Evaluate $16 - 36 x^{2}$ when:

75.

A painter drops a brush from a platform 75 feet high. The polynomial $−16 t^{2} + 75$ gives the height of the brush $t$ seconds after it was dropped. Find the height after $t = 2$ seconds.

76.

A girl drops a ball off a cliff into the ocean. The polynomial $−16 t^{2} + 250$ gives the height of a ball $t$ seconds after it is dropped from a 250-foot tall cliff. Find the height after $t = 2$ seconds.

77.

A manufacturer of stereo sound speakers has found that the revenue received from selling the speakers at a cost of p dollars each is given by the polynomial $−4 p^{2} + 420 p .$ Find the revenue received when $p = 60$ dollars.

78.

A manufacturer of the latest basketball shoes has found that the revenue received from selling the shoes at a cost of p dollars each is given by the polynomial $−4 p^{2} + 420 p .$ Find the revenue received when $p = 90$ dollars.

Everyday Math

79.

Fuel Efficiency The fuel efficiency (in miles per gallon) of a car going at a speed of $x$ miles per hour is given by the polynomial $- \frac{1}{150} x^{2} + \frac{1}{3} x$ . Find the fuel efficiency when $x = 30 mph$ .

80.

Stopping Distance The number of feet it takes for a car traveling at $x$ miles per hour to stop on dry, level concrete is given by the polynomial $0.06 x^{2} + 1.1 x$ . Find the stopping distance when $x = 40 mph$ .

81.

Rental Cost The cost to rent a rug cleaner for $d$ days is given by the polynomial $5.50 d + 25$ . Find the cost to rent the cleaner for 6 days.

82.

Height of Projectile The height (in feet) of an object projected upward is given by the polynomial $−16 t^{2} + 60 t + 90$ where $t$ represents time in seconds. Find the height after $t = 2.5$ seconds.

83.

Temperature Conversion The temperature in degrees Fahrenheit is given by the polynomial $\frac{9}{5} c + 32$ where $c$ represents the temperature in degrees Celsius. Find the temperature in degrees Fahrenheit when $c = 65 ° .$

Writing Exercises

84.

Using your own words, explain the difference between a monomial, a binomial, and a trinomial.

85.

Using your own words, explain the difference between a polynomial with five terms and a polynomial with a degree of 5.

86.

Ariana thinks the sum $6 y^{2} + 5 y^{4}$ is $11 y^{6}$ . What is wrong with her reasoning?

87.

Jonathan thinks that $\frac{1}{3}$ and $\frac{1}{x}$ are both monomials. What is wrong with his reasoning?

Self Check

ⓐ After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section.

This is a table that has six rows and four columns. In the first row, which is a header row, the cells read from left to right “I can…,” “Confidently,” “With some help,” and “No-I don’t get it!” The first column below “I can…” reads “identify polynomials, monomials, binomials, and trinomials,” “determine the degree of polynomials,” “add and subtract monomials,” “add and subtract polynomials,” and “evaluate a polynomial for a given value.” The rest of the cells are blank.

ⓑ If most of your checks were:

…confidently. Congratulations! You have achieved the objectives in this section. Reflect on the study skills you used so that you can continue to use them. What did you do to become confident of your ability to do these things? Be specific.

…with some help. This must be addressed quickly because topics you do not master become potholes in your road to success. In math every topic builds upon previous work. It is important to make sure you have a strong foundation before you move on. Whom can you ask for help? Your fellow classmates and instructor are good resources. Is there a place on campus where math tutors are available? Can your study skills be improved?

…no - I don’t get it! This is a warning sign and you must not ignore it. You should get help right away or you will quickly be overwhelmed. See your instructor as soon as you can to discuss your situation. Together you can come up with a plan to get you the help you need.