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( x + 5 ) ( x 5 ) = x 2 25 ( x + 11 ) ( x 11 ) = x 2 121 ( 2 x + 3 ) ( 2 x 3 ) = 4 x 2 9

Because the sign changes in the second binomial, the outer and inner terms cancel each other out, and we are left only with the square of the first term minus the square of the last term.

Is there a special form for the sum of squares?

No. The difference of squares occurs because the opposite signs of the binomials cause the middle terms to disappear. There are no two binomials that multiply to equal a sum of squares.

Difference of squares

When a binomial is multiplied by a binomial with the same terms separated by the opposite sign, the result is the square of the first term minus the square of the last term.

( a + b ) ( a b ) = a 2 b 2

Given a binomial multiplied by a binomial with the same terms but the opposite sign, find the difference of squares.

  1. Square the first term of the binomials.
  2. Square the last term of the binomials.
  3. Subtract the square of the last term from the square of the first term.

Multiplying binomials resulting in a difference of squares

Multiply ( 9 x + 4 ) ( 9 x 4 ) .

Square the first term to get ( 9 x ) 2 = 81 x 2 . Square the last term to get 4 2 = 16. Subtract the square of the last term from the square of the first term to find the product of 81 x 2 16.

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Multiply ( 2 x + 7 ) ( 2 x 7 ) .

4 x 2 −49

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Performing operations with polynomials of several variables

We have looked at polynomials containing only one variable. However, a polynomial can contain several variables. All of the same rules apply when working with polynomials containing several variables. Consider an example:

( a + 2 b ) ( 4 a b c ) a ( 4 a b c ) + 2 b ( 4 a b c ) Use the distributive property . 4 a 2 a b a c + 8 a b 2 b 2 2 b c Multiply . 4 a 2 + ( a b + 8 a b ) a c 2 b 2 2 b c Combine like terms . 4 a 2 + 7 a b a c 2 b c 2 b 2 Simplify .

Multiplying polynomials containing several variables

Multiply ( x + 4 ) ( 3 x 2 y + 5 ) .

Follow the same steps that we used to multiply polynomials containing only one variable.

x ( 3 x 2 y + 5 ) + 4 ( 3 x 2 y + 5 )   Use the distributive property . 3 x 2 2 x y + 5 x + 12 x 8 y + 20 Multiply . 3 x 2 2 x y + ( 5 x + 12 x ) 8 y + 20 Combine like terms . 3 x 2 2 x y + 17 x 8 y + 20   Simplify .
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Multiply ( 3 x 1 ) ( 2 x + 7 y 9 ) .

6 x 2 + 21 x y −29 x −7 y + 9

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

Key equations

perfect square trinomial ( x + a ) 2 = ( x + a ) ( x + a ) = x 2 + 2 a x + a 2
difference of squares ( a + b ) ( a b ) = a 2 b 2

Key concepts

  • A polynomial is a sum of terms each consisting of a variable raised to a non-negative integer power. The degree is the highest power of the variable that occurs in the polynomial. The leading term is the term containing the highest degree, and the leading coefficient is the coefficient of that term. See [link] .
  • We can add and subtract polynomials by combining like terms. See [link] and [link] .
  • To multiply polynomials, use the distributive property to multiply each term in the first polynomial by each term in the second. Then add the products. See [link] .
  • FOIL (First, Outer, Inner, Last) is a shortcut that can be used to multiply binomials. See [link] .
  • Perfect square trinomials and difference of squares are special products. See [link] and [link] .
  • Follow the same rules to work with polynomials containing several variables. See [link] .

Section exercises

Verbal

Evaluate the following statement: The degree of a polynomial in standard form is the exponent of the leading term. Explain why the statement is true or false.

The statement is true. In standard form, the polynomial with the highest value exponent is placed first and is the leading term. The degree of a polynomial is the value of the highest exponent, which in standard form is also the exponent of the leading term.

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Many times, multiplying two binomials with two variables results in a trinomial. This is not the case when there is a difference of two squares. Explain why the product in this case is also a binomial.

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You can multiply polynomials with any number of terms and any number of variables using four basic steps over and over until you reach the expanded polynomial. What are the four steps?

Use the distributive property, multiply, combine like terms, and simplify.

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State whether the following statement is true and explain why or why not: A trinomial is always a higher degree than a monomial.

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Algebraic

For the following exercises, identify the degree of the polynomial.

14 m 3 + m 2 16 m + 8

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200 p 30 p 2 m + 40 m 3

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6 y 4 y 5 + 3 y 4

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For the following exercises, find the sum or difference.

( 12 x 2 + 3 x ) ( 8 x 2 −19 )

4 x 2 + 3 x + 19

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( 4 z 3 + 8 z 2 z ) + ( −2 z 2 + z + 6 )

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( 6 w 2 + 24 w + 24 ) ( 3 w 2 6 w + 3 )

3 w 2 + 30 w + 21

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( 7 a 3 + 6 a 2 4 a 13 ) + ( 3 a 3 4 a 2 + 6 a + 17 )

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( 11 b 4 6 b 3 + 18 b 2 4 b + 8 ) ( 3 b 3 + 6 b 2 + 3 b )

11 b 4 −9 b 3 + 12 b 2 −7 b + 8

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( 49 p 2 25 ) + ( 16 p 4 32 p 2 + 16 )

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For the following exercises, find the product.

( 4 x + 2 ) ( 6 x 4 )

24 x 2 −4 x −8

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( 14 c 2 + 4 c ) ( 2 c 2 3 c )

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( 6 b 2 6 ) ( 4 b 2 4 )

24 b 4 −48 b 2 + 24

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( 3 d 5 ) ( 2 d + 9 )

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( 9 v 11 ) ( 11 v 9 )

99 v 2 −202 v + 99

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( 4 t 2 + 7 t ) ( −3 t 2 + 4 )

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( 8 n 4 ) ( n 2 + 9 )

8 n 3 −4 n 2 + 72 n −36

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For the following exercises, expand the binomial.

( 3 y 7 ) 2

9 y 2 −42 y + 49

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( 4 p + 9 ) 2

16 p 2 + 72 p + 81

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( 3 y 6 ) 2

9 y 2 −36 y + 36

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For the following exercises, multiply the binomials.

( 4 c + 1 ) ( 4 c 1 )

16 c 2 −1

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( 9 a 4 ) ( 9 a + 4 )

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( 15 n 6 ) ( 15 n + 6 )

225 n 2 −36

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( 25 b + 2 ) ( 25 b 2 )

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( 4 + 4 m ) ( 4 4 m )

−16 m 2 + 16

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( 14 p + 7 ) ( 14 p 7 )

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( 11 q 10 ) ( 11 q + 10 )

121 q 2 −100

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For the following exercises, multiply the polynomials.

( 2 x 2 + 2 x + 1 ) ( 4 x 1 )

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( 4 t 2 + t 7 ) ( 4 t 2 1 )

16 t 4 + 4 t 3 −32 t 2 t + 7

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( x 1 ) ( x 2 2 x + 1 )

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( y 2 ) ( y 2 4 y 9 )

y 3 −6 y 2 y + 18

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( 6 k 5 ) ( 6 k 2 + 5 k 1 )

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( 3 p 2 + 2 p 10 ) ( p 1 )

3 p 3 p 2 −12 p + 10

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( 4 m 13 ) ( 2 m 2 7 m + 9 )

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( a + b ) ( a b )

a 2 b 2

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( 4 x 6 y ) ( 6 x 4 y )

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( 4 t 5 u ) 2

16 t 2 −40 t u + 25 u 2

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( 9 m + 4 n 1 ) ( 2 m + 8 )

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( 4 t x ) ( t x + 1 )

4 t 2 + x 2 + 4 t −5 t x x

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( b 2 1 ) ( a 2 + 2 a b + b 2 )

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( 4 r d ) ( 6 r + 7 d )

24 r 2 + 22 r d −7 d 2

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( x + y ) ( x 2 x y + y 2 )

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Real-world applications

A developer wants to purchase a plot of land to build a house. The area of the plot can be described by the following expression: ( 4 x + 1 ) ( 8 x 3 ) where x is measured in meters. Multiply the binomials to find the area of the plot in standard form.

32 x 2 −4 x −3 m 2

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A prospective buyer wants to know how much grain a specific silo can hold. The area of the floor of the silo is ( 2 x + 9 ) 2 . The height of the silo is 10 x + 10 , where x is measured in feet. Expand the square and multiply by the height to find the expression that shows how much grain the silo can hold.

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Extensions

For the following exercises, perform the given operations.

( 4 t 7 ) 2 ( 2 t + 1 ) ( 4 t 2 + 2 t + 11 )

32 t 3 100 t 2 + 40 t + 38

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( 3 b + 6 ) ( 3 b 6 ) ( 9 b 2 36 )

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( a 2 + 4 a c + 4 c 2 ) ( a 2 4 c 2 )

a 4 + 4 a 3 c −16 a c 3 −16 c 4

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Questions & Answers

how did you get 1640
Noor Reply
If auger is pair are the roots of equation x2+5x-3=0
Peter Reply
Wayne and Dennis like to ride the bike path from Riverside Park to the beach. Dennis’s speed is seven miles per hour faster than Wayne’s speed, so it takes Wayne 2 hours to ride to the beach while it takes Dennis 1.5 hours for the ride. Find the speed of both bikers.
MATTHEW Reply
420
Sharon
from theory: distance [miles] = speed [mph] × time [hours] info #1 speed_Dennis × 1.5 = speed_Wayne × 2 => speed_Wayne = 0.75 × speed_Dennis (i) info #2 speed_Dennis = speed_Wayne + 7 [mph] (ii) use (i) in (ii) => [...] speed_Dennis = 28 mph speed_Wayne = 21 mph
George
Let W be Wayne's speed in miles per hour and D be Dennis's speed in miles per hour. We know that W + 7 = D and W * 2 = D * 1.5. Substituting the first equation into the second: W * 2 = (W + 7) * 1.5 W * 2 = W * 1.5 + 7 * 1.5 0.5 * W = 7 * 1.5 W = 7 * 3 or 21 W is 21 D = W + 7 D = 21 + 7 D = 28
Salma
Devon is 32 32​​ years older than his son, Milan. The sum of both their ages is 54 54​. Using the variables d d​ and m m​ to represent the ages of Devon and Milan, respectively, write a system of equations to describe this situation. Enter the equations below, separated by a comma.
Aaron Reply
find product (-6m+6) ( 3m²+4m-3)
SIMRAN Reply
-42m²+60m-18
Salma
what is the solution
bill
how did you arrive at this answer?
bill
-24m+3+3mÁ^2
Susan
i really want to learn
Amira
I only got 42 the rest i don't know how to solve it. Please i need help from anyone to help me improve my solving mathematics please
Amira
Hw did u arrive to this answer.
Aphelele
hi
Bajemah
-6m(3mA²+4m-3)+6(3mA²+4m-3) =-18m²A²-24m²+18m+18mA²+24m-18 Rearrange like items -18m²A²-24m²+42m+18A²-18
Salma
complete the table of valuesfor each given equatio then graph. 1.x+2y=3
Jovelyn Reply
x=3-2y
Salma
y=x+3/2
Salma
Hi
Enock
given that (7x-5):(2+4x)=8:7find the value of x
Nandala
3x-12y=18
Kelvin
please why isn't that the 0is in ten thousand place
Grace Reply
please why is it that the 0is in the place of ten thousand
Grace
Send the example to me here and let me see
Stephen
A meditation garden is in the shape of a right triangle, with one leg 7 feet. The length of the hypotenuse is one more than the length of one of the other legs. Find the lengths of the hypotenuse and the other leg
Marry Reply
how far
Abubakar
cool u
Enock
state in which quadrant or on which axis each of the following angles given measure. in standard position would lie 89°
Abegail Reply
hello
BenJay
hi
Method
I am eliacin, I need your help in maths
Rood
how can I help
Sir
hmm can we speak here?
Amoon
however, may I ask you some questions about Algarba?
Amoon
hi
Enock
what the last part of the problem mean?
Roger
The Jones family took a 15 mile canoe ride down the Indian River in three hours. After lunch, the return trip back up the river took five hours. Find the rate, in mph, of the canoe in still water and the rate of the current.
cameron Reply
Shakir works at a computer store. His weekly pay will be either a fixed amount, $925, or $500 plus 12% of his total sales. How much should his total sales be for his variable pay option to exceed the fixed amount of $925.
mahnoor Reply
I'm guessing, but it's somewhere around $4335.00 I think
Lewis
12% of sales will need to exceed 925 - 500, or 425 to exceed fixed amount option. What amount of sales does that equal? 425 ÷ (12÷100) = 3541.67. So the answer is sales greater than 3541.67. Check: Sales = 3542 Commission 12%=425.04 Pay = 500 + 425.04 = 925.04. 925.04 > 925.00
Munster
difference between rational and irrational numbers
Arundhati Reply
When traveling to Great Britain, Bethany exchanged $602 US dollars into £515 British pounds. How many pounds did she receive for each US dollar?
Jakoiya Reply
how to reduced echelon form
Solomon Reply
Jazmine trained for 3 hours on Saturday. She ran 8 miles and then biked 24 miles. Her biking speed is 4 mph faster than her running speed. What is her running speed?
Zack Reply
d=r×t the equation would be 8/r+24/r+4=3 worked out
Sheirtina
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Source:  OpenStax, College algebra. OpenStax CNX. Feb 06, 2015 Download for free at https://legacy.cnx.org/content/col11759/1.3
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