CHAPTER 8 Polynomials

8.1 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

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. 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{array}{lllll}\text{Polynomial} & b+1 & 4{y}^{2}-7y+2 \qquad & 4{x}^{4}+{x}^{3}+8{x}^{2}-9x+1&\\ \text{Monomial}& 14& 8{y}^{2} & -9{x}^{3}{y}^{5} & -13 \\ \text{Binomial} &a+7& 4b-5 & {y}^{2}-16 & 3{x}^{3}-9{x}^{2} \\ \text{Trinomial} & {x}^{2}-7x+12 \qquad & 9{y}^{2}+2y-8 \qquad & 6{m}^{4}-{m}^{3}+8m & {z}^{4}+3{z}^{2}-1\hfill \end{array}

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 1

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

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

TRY IT 1.1

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

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

Show answer

a) monomial b) polynomial c) trinomial d) binomial e) monomial

TRY IT 1.2

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

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

Show answer

a) binomial b) trinomial c) monomial d) polynomial e) monomial

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 2

Find the degree of the following polynomials.

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

EXAMPLE 2.1

Find the degree of the following polynomials:

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

Show answer

a) 1 b) 4 c) 12 d) 3 e) 0

TRY IT 2.2

Find the degree of the following polynomials:

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

Show answer

a) 0 b) 5 c) 1 d) 2 e) 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 3

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

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

TRY IT 3.1

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

Show answer

21{q}^{2}

TRY 3.2

Add: -15{c}^{2}+8{c}^{2}.

Show answer

-7{c}^{2}

EXAMPLE 4

Subtract: 16p-\left(-7p\right).

Solution
16p-\left(-7p\right)
Combine like terms. 23p

TRY IT 4.1

Subtract: 8m-\left(-5m\right).

Show answer

13m

TRY IT 4.2

Subtract: -15{z}^{3}-\left(-5{z}^{3}\right).

Show answer

-10{z}^{3}

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

EXAMPLE 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}

TRY IT 5.1

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

Show answer

5{y}^{2}+3{z}^{2}

TRY IT 5.2

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

Show answer

-4{m}^{2}+{n}^{2}

EXAMPLE 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}

TRY IT 6.1

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

Show answer

There are no like terms to combine.

TRY IT 6.2

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

Show answer

There are no like terms to combine.

Add and Subtract Polynomials

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 7

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

Solution
Identify like terms. 5 y squared minus 3 y plus 15, plus 3 y squared minus 4 y minus 11.
Rearrange to get the like terms together. 5y squared plus 3y squared, identified as like terms, minus 3y minus 4y, identified as like terms, plus 15 minus 11, identified as like terms.
Combine like terms. 8 y squared minus 7y plus 4.

TRY IT 7.1

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

Show answer

8{x}^{2}-11x+1

TRY IT 7.2

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

Show answer

17{y}^{2}+14y+1

EXAMPLE 8

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

Solution
9 w squared minus 7 w plus 5, minus 2 w squared minus 4.
Distribute and identify like terms. 9 w squared and 2 w squared are like terms. 5 and 4 are also like terms.
Rearrange the terms. 9 w squared minus 2 w squared minus 7 w plus 5 plus 4.
Combine like terms. 7 w squared minus 7 w plus 9.

TRY IT 8.1

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

Show answer

15{x}^{2}+3x-5

TRY IT 8.2

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

Show answer

6{b}^{2}+3

EXAMPLE 9

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

Solution
.
7 c squared minus 5 c plus 3, minus c squared minus 4c plus 7.
Distribute and identify like terms. 7 c squared and c squared are like terms. Minus 5c and 4c are like terms. 3 and minus 7 are like terms.
Rearrange the terms. 7 c squared minus c squared minus 5 c plus 4 c plus 3 minus 7.
Combine like terms. 6 c squared minus c minus 4.

TRY IT 9.1

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

Show answer

2{z}^{2}+12z-2

TRY IT 9.2

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

Show answer

5{x}^{2}+14x+7

EXAMPLE 10

Find the sum: \left({u}^{2}-6uv+5{v}^{2}\right)+\left(3{u}^{2}+2uv\right).

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

EXAMPLE 10.1

Find the sum: \left(3{x}^{2}-4xy+5{y}^{2}\right)+\left(2{x}^{2}-xy\right).

Show answer

5{x}^{2}-5xy+5{y}^{2}

EXAMPLE 10.2

Find the sum: \left(2{x}^{2}-3xy-2{y}^{2}\right)+\left(5{x}^{2}-3xy\right).

Show answer

7{x}^{2}-6xy-2{y}^{2}

EXAMPLE 11.1

Find the difference: \left({p}^{2}+{q}^{2}\right)-\left({p}^{2}+10pq-2{q}^{2}\right).

Solution
\left({p}^{2}+{q}^{2}\right)-\left({p}^{2}+10pq-2{q}^{2}\right)
Distribute. {p}^{2}+{q}^{2}-{p}^{2}-10pq+2{q}^{2}
Rearrange the terms, to put like terms together. {p}^{2}-{p}^{2}-10pq+{q}^{2}+2{q}^{2}
Combine like terms. -10p{q}^{2}+3{q}^{2}

TRY IT 11.1

Find the difference: \left({a}^{2}+{b}^{2}\right)-\left({a}^{2}+5ab-6{b}^{2}\right).

Show answer

-5ab-5{b}^{2}

TRY IT 11.2

Find the difference: \left({m}^{2}+{n}^{2}\right)-\left({m}^{2}-7mn-3{n}^{2}\right).

Show answer

4{n}^{2}+7mn

EXAMPLE 12

Simplify: \left({a}^{3}-{a}^{2}b\right)-\left(a{b}^{2}+{b}^{3}\right)+\left({a}^{2}b+a{b}^{2}\right).

Solution
\left({a}^{3}-{a}^{2}b\right)-\left(a{b}^{2}+{b}^{3}\right)+\left({a}^{2}b+a{b}^{2}\right)
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}

TRY IT 12.1

Simplify: \left({x}^{3}-{x}^{2}y\right)-\left(x{y}^{2}+{y}^{3}\right)+\left({x}^{2}y+x{y}^{2}\right).

Show answer

{x}^{3}-{y}^{3}

TRY IT 12.2

Simplify: \left({p}^{3}-{p}^{2}q\right)+\left(p{q}^{2}+{q}^{3}\right)-\left({p}^{2}q+p{q}^{2}\right).

Show answer

{p}^{3}-2{p}^{2}q+{q}^{3}

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 13

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

  1. x=4
  2. x=-2
  3. x=0
Solution
a) x=4
5 x squared minus 8 x plus 4.
Substitute 4 for x. 5 times 4 squared minus 8 times 4 plus 4.
Simplify the exponents. 5 times 16 minus 8 times 4 plus 4.
Multiply. 80 minus 32 plus 4.
Simplify. 52.
b) x=-2
5 x squared minus 8 x plus 4.
Substitute negative 2 for x. 5 times negative 2 squared minus 8 times negative 2 plus 4.
Simplify the exponents. 5 times 4 minus 8 times negative 2 plus 4.
Multiply. 20 plus 16 plus 4.
Simplify. 40.
c) x=0
5 x squared minus 8 x plus 4.
Substitute 0 for x. 5 times 0 squared minus 8 times 0 plus 4.
Simplify the exponents. 5 times 0 minus 8 times 0 plus 4.
Multiply. 0 plus 0 plus 4.
Simplify. 4.

TRY IT 13.1

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

  1. x=3
  2. x=-5
  3. x=0
Show answer

a) 18 b) 50 c) -15

TRY IT 13.2

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

  1. z=-2
  2. z=0
  3. z=2
Show answer

a) 18 b) -4 c) 14

EXAMPLE 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{\left(2\right)}^{2}+250
Simplify. -16\cdot 4+250
Simplify. -64+250
Simplify. 186
After 2 seconds the height of the ball is 186 feet.

TRY IT 14.1

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.

Show answer

250

TRY IT 14.2

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.

Show answer

106

EXAMPLE 15

The polynomial 6{x}^{2}+15xy 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
6 x squared plus 15 x y.
Substitute x equals 4 and y equals 6. 6 times 4 squared plus 15 times 4 times 6.
Simplify. 6 times 16 plus 15 times 4 times 6.
Simplify. 96 plus 360.
Simplify. 456.
The cost of producing the box is $456.

TRY IT 15.1

The polynomial 6{x}^{2}+15xy 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=6 feet and y=4 feet.

Show answer

$576

TRY IT 15.2

The polynomial 6{x}^{2}+15xy 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=5 feet and y=8 feet.

Show answer

$750

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

Key Concepts

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

Glossary

binomial
A binomial is a polynomial with exactly two terms.
degree of a constant
The degree of any constant is 0.
degree of a polynomial
The degree of a polynomial is the highest degree of all its terms.
degree of a term
The degree of a term is the exponent of its variable.
monomial
A monomial is a term of the form a{x}^{m}, where a is a constant and m is a whole number; a monomial has exactly one term.
polynomial
A polynomial is a monomial, or two or more monomials combined by addition or subtraction.
standard form
A polynomial is in standard form when the terms of a polynomial are written in descending order of degrees.
trinomial
A trinomial is a polynomial with exactly three terms.

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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.

1.

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

2.

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

3.

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

4.

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


Determine the Degree of Polynomials

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

5.

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

6.

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

7.

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

8.

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


Add and Subtract Monomials

In the following exercises, add or subtract the monomials.

9. {7x}^{2}+5{x}^{2} 10. {4y}^{3}+6{y}^{3}
11. -12w+18w 12. -3m+9m
13. \text{4a}-9a 14. -y-5y
15. 28x-\left(-12x\right) 16. 13z-\left(-4z\right)
17. -5b-17b 18. -10x-35x
19. 12a+5b-22a 20. \text{14x}-3y-13x
21. 2{a}^{2}+{b}^{2}-6{a}^{2} 22. 5{u}^{2}+4{v}^{2}-6{u}^{2}
23. x{y}^{2}-5x-5{y}^{2} 24. p{q}^{2}-4p-3{q}^{2}
25. {a}^{2}b-4a-5a{b}^{2} 26. {x}^{2}y-3x+7x{y}^{2}
27. \text{12a}+8b 28. \text{19y}+5z
29. Add: 4a,-3b,-8a 30. Add: 4x,3y,-3x
31. Subtract 5{x}^{6}\text{from}-12{x}^{6}. 32. Subtract 2{p}^{4}\text{from}-7{p}^{4}.

Add and Subtract Polynomials

In the following exercises, add or subtract the polynomials.

33. \left(5{y}^{2}+12y+4\right)+\left(6{y}^{2}-8y+7\right) 34. \left(4{y}^{2}+10y+3\right)+\left(8{y}^{2}-6y+5\right)
35. \left({x}^{2}+6x+8\right)+\left(-4{x}^{2}+11x-9\right) 36. \left({y}^{2}+9y+4\right)+\left(-2{y}^{2}-5y-1\right)
37. \left(8{x}^{2}-5x+2\right)+\left(3{x}^{2}+3\right) 38. \left(7{x}^{2}-9x+2\right)+\left(6{x}^{2}-4\right)
39. \left(5{a}^{2}+8\right)+\left({a}^{2}-4a-9\right) 40. \left({p}^{2}-6p-18\right)+\left(2{p}^{2}+11\right)
41. \left(4{m}^{2}-6m-3\right)-\left(2{m}^{2}+m-7\right) 42. \left(3{b}^{2}-4b+1\right)-\left(5{b}^{2}-b-2\right)
43. \left({a}^{2}+8a+5\right)-\left({a}^{2}-3a+2\right) 44. \left({b}^{2}-7b+5\right)-\left({b}^{2}-2b+9\right)
45. \left(12{s}^{2}-15s\right)-\left(s-9\right) 46. \left(10{r}^{2}-20r\right)-\left(r-8\right)
47. Subtract \left(9{x}^{2}+2\right) from \left(12{x}^{2}-x+6\right). 48. Subtract \left(5{y}^{2}-y+12\right) from \left(10{y}^{2}-8y-20\right).
49. Subtract \left(7{w}^{2}-4w+2\right) from \left(8{w}^{2}-w+6\right). 50. Subtract \left(5{x}^{2}-x+12\right) from \left(9{x}^{2}-6x-20\right).
51. Find the sum of \left(2{p}^{3}-8\right) and \left({p}^{2}+9p+18\right). 52. Find the sum of \left({q}^{2}+4q+13\right) and \left(7{q}^{3}-3\right).
53. Find the sum of \left(8{a}^{3}-8a\right) and \left({a}^{2}+6a+12\right). 54. Find the sum of \left({b}^{2}+5b+13\right) and \left(4{b}^{3}-6\right).
55. Find the difference of
\left({w}^{2}+w-42\right) and
\left({w}^{2}-10w+24\right).		 56. Find the difference of
\left({z}^{2}-3z-18\right) and
\left({z}^{2}+5z-20\right).
57. Find the difference of
\left({c}^{2}+4c-33\right) and
\left({c}^{2}-8c+12\right).		 58. Find the difference of
\left({t}^{2}-5t-15\right) and
\left({t}^{2}+4t-17\right).
59. \left(7{x}^{2}-2xy+6{y}^{2}\right)+\left(3{x}^{2}-5xy\right) 60. \left(-5{x}^{2}-4xy-3{y}^{2}\right)+\left(2{x}^{2}-7xy\right)
61. \left(7{m}^{2}+mn-8{n}^{2}\right)+\left(3{m}^{2}+2mn\right) 62. \left(2{r}^{2}-3rs-2{s}^{2}\right)+\left(5{r}^{2}-3rs\right)
63. \left({a}^{2}-{b}^{2}\right)-\left({a}^{2}+3ab-4{b}^{2}\right) 64. \left({m}^{2}+2{n}^{2}\right)-\left({m}^{2}-8mn-{n}^{2}\right)
65. \left({u}^{2}-{v}^{2}\right)-\left({u}^{2}-4uv-3{v}^{2}\right) 66. \left({j}^{2}-{k}^{2}\right)-\left({j}^{2}-8jk-5{k}^{2}\right)
67. \left({p}^{3}-3{p}^{2}q\right)+\left(2p{q}^{2}+4{q}^{3}\right)-\left(3{p}^{2}q+p{q}^{2}\right) 68. \left({a}^{3}-2{a}^{2}b\right)+\left(a{b}^{2}+{b}^{3}\right)-\left(3{a}^{2}b+4a{b}^{2}\right)
69. \left({x}^{3}-{x}^{2}y\right)-\left(4x{y}^{2}-{y}^{3}\right)+\left(3{x}^{2}y-x{y}^{2}\right) 70. \left({x}^{3}-2{x}^{2}y\right)-\left(x{y}^{2}-3{y}^{3}\right)-\left({x}^{2}y-4x{y}^{2}\right)

Evaluate a Polynomial for a Given Value

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

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

a) y=5
b) y=-2
c) y=0

72. Evaluate 5{y}^{2}-y-7 when:

a) y=-4
b) y=1
c) y=0

73. Evaluate 4-36x when:

a) x=3
b) x=0
c) x=-1

74. Evaluate 16-36{x}^{2} when:

a) x=-1
b) x=0
c) x=2
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}+420p. 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}+420p. 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 -\dfrac{1}{150}{x}^{2}+\dfrac{1}{3}x. Find the fuel efficiency when x=30 \text{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}+1.1x. Find the stopping distance when x=40\text{mph}.
81. Rental Cost The cost to rent a rug cleaner for d days is given by the polynomial 5.50d+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}+60t+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 \dfrac{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 \dfrac{1}{3} and \dfrac{1}{x} are both monomials. What is wrong with his reasoning?

Answers:

1. a) trinomial b) polynomial c) binomial d) monomial e) binomial 3. a) binomial b) trinomial c) polynomial d) trinomial e) monomial
5. a) 2 b) 4 c) 1 d) 3 e) 0 7. a) 1 b) 2 c) 3 d) 3 e) 0
9. 12{x}^{2} 11. 6w
13. -5a 15. 40x
17. -22b 19. -10a+5b
21. -4{a}^{2}+{b}^{2} 21. -4{a}^{2}+{b}^{2}
25. {a}^{2}b-4a-5a{b}^{2} 27. \text{12a}+8b
29. -4a-3b 31. -17{x}^{6}
33. 11{y}^{2}+4y+11 35. -3{x}^{2}+17x-1
37. 11{x}^{2}-5x+5 39. 6{a}^{2}-4a-1
41. 2{m}^{2}-7m+4 43. 11a+3
45. 12{s}^{2}-14s+9 47. 3{x}^{2}-x+4
49. {w}^{2}+3w+4 51. 2{p}^{3}+{p}^{2}+9p+10
51. 2{p}^{3}+{p}^{2}+9p+10 55. 11w-64
57. 12c-45 59. 10{x}^{2}-7xy+6{y}^{2}
61. 10{m}^{2}+3mn-8{n}^{2} 63. -3ab+3{b}^{2}
65. 4uv+2{v}^{2} 67. {p}^{3}-6{p}^{2}q+p{q}^{2}+4{q}^{3}
69. {x}^{3}+2{x}^{2}y-5x{y}^{2}+{y}^{3} 71. a) 187 b) 46 c) 2
73. a) −104 b) 4 c) 40 75. 11
77. $10,800 77. $10,800
81. $58 83. 149
85. Answers will vary. 87. Answers will vary.

Attributions

This chapter has been adapted from “Add and Subtract Polynomials” in Prealgebra (OpenStax) by Lynn Marecek, MaryAnne Anthony-Smith, and Andrea Honeycutt Mathis, which is under a CC BY 4.0 Licence. Adapted by Izabela Mazur. See the Copyright page for more information.

License

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Introductory Algebra Copyright © 2021 by Izabela Mazur is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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