Introduction to Factoring Polynomials
Find the Greatest Common Factor of Two or More Expressions
Earlier we multiplied factors together to get a product. Now, we will be reversing this process; we will start with a product and then break it down into its factors. Splitting a product into factors is called factoring.
In The Language of Algebra we factored numbers to find the least common multiple (LCM) of two or more numbers. Now we will factor expressions and find the greatest common factor of two or more expressions. The method we use is similar to what we used to find the LCM.
First we will find the greatest common factor of two numbers.
Find the greatest common factor of and
Solution
Solution
| Step 1: Factor each coefficient into primes. Write all variables with exponents in expanded form. | Factor 24 and 36. | ![]() |
| Step 2: List all factors--matching common factors in a column. | ![]() |
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| In each column, circle the common factors. | Circle the 2, 2, and 3 that are shared by both numbers. | ![]() |
| Step 3: Bring down the common factors that all expressions share. | Bring down the 2, 2, 3 and then multiply. | |
| Step 4: Multiply the factors. | The GCF of 24 and 36 is 12. |
Notice that since the GCF is a factor of both numbers, and can be written as multiples of
In the previous example, we found the greatest common factor of constants. The greatest common factor of an algebraic expression can contain variables raised to powers along with coefficients. We summarize the steps we use to find the greatest common factor.
Find the greatest common factor of
Solution
Solution
| Factor each number into primes. Circle the common factors in each column. Bring down the common factors. |
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| The GCF of 5x and 15 is 5. |
In the examples so far, the greatest common factor was a constant. In the next two examples we will get variables in the greatest common factor.
Find the greatest common factor of and
Solution
Solution
| Factor each coefficient into primes and write
the variables with exponents in expanded form. Circle the common factors in each column. Bring down the common factors. Multiply the factors. |
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Find the greatest common factor of
Solution
Solution
| Factor each coefficient into primes and write
the variables with exponents in expanded form. Circle the common factors in each column. Bring down the common factors. Multiply the factors. |
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Factor the Greatest Common Factor from a Polynomial
Just like in arithmetic, where it is sometimes useful to represent a number in factored form (for example, as in algebra it can be useful to represent a polynomial in factored form. One way to do this is by finding the greatest common factor of all the terms. Remember that you can multiply a polynomial by a monomial as follows:
Here, we will start with a product, like and end with its factors, To do this we apply the Distributive Property “in reverse”.
The form on the left is used to multiply. The form on the right is used to factor.
So how do we use the Distributive Property to factor a polynomial? We find the GCF of all the terms and write the polynomial as a product!
Factor:
Solution
Solution
| Step 1: Find the GCF of all the terms of the polynomial. | Find the GCF of 2x and 14. | ![]() |
| Step 2: Rewrite each term as a product using the GCF. | Rewrite 2x and 14 as products of their GCF, 2. |
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| Step 3: Use the Distributive Property 'in reverse' to factor the expression. | ||
| Step 4: Check by multiplying the factors. | Check:
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Notice that in Example 5, we used the word factor as both a noun and a verb:
Factor:
Solution
Solution
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| Rewrite each term as a product using the GCF. | ![]() |
| Use the Distributive Property 'in reverse' to factor the GCF. | ![]() |
| Check by multiplying the factors to get the original polynomial. | |
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The expressions in the next example have several factors in common. Remember to write the GCF as the product of all the common factors.
Factor:
Solution
Solution
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| Rewrite each term as a product using the GCF. | ![]() |
| Factor the GCF. | ![]() |
| Check by multiplying the factors. | |
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Now we’ll factor the greatest common factor from a trinomial. We start by finding the GCF of all three terms.
Factor:
Solution
Solution
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| Rewrite each term as a product using the GCF. | ![]() |
| Factor the GCF. | ![]() |
| Check by multiplying. | |
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In the next example, we factor a variable from a binomial.
Factor:
Solution
Solution
| Find the GCF of and and the math that goes with it. | ![]() |
| Rewrite each term as a product. | ![]() |
| Factor the GCF. | |
| Check by multiplying. | |
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When there are several common factors, as we’ll see in the next two examples, good organization and neat work helps!
Factor:
Solution
Solution
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| Rewrite each term. | ![]() |
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| Factor the GCF. | ![]() |
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| Check. | ![]() |
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Factor:
Solution
Solution
| Find the GCF of and | ![]() |
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| Rewrite each term. | ![]() |
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| Factor the GCF. | ![]() |
Factor:
Solution
Solution
Previously, we found the GCF of to be
| Rewrite each term using the GCF, 2x. | ![]() |
| Factor the GCF. | |
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When the leading coefficient, the coefficient of the first term, is negative, we factor the negative out as part of the GCF.
Factor:
Solution
Solution
| When the leading coefficient is negative, the GCF will be negative. Ignoring the signs of the terms, we first find the GCF of 9y and 27 is 9. | ![]() |
| Since the expression −9y−27 has a negative leading coefficient, we use −9 as the GCF. | |
| Rewrite each term using the GCF. | ![]() |
| Factor the GCF. | |
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Pay close attention to the signs of the terms in the next example.
Factor:
Solution
Solution
| The leading coefficient is negative, so the GCF will be negative. | |
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| Since the leading coefficient is negative, the GCF is negative, −4a. | |
| Rewrite each term. | ![]() |
| Factor the GCF. | |
| Check on your own by multiplying. | |
Key Concepts
-
Find the greatest common factor.
- Factor each coefficient into primes. Write all variables with exponents in expanded form.
- List all factors—matching common factors in a column. In each column, circle the common factors.
- Bring down the common factors that all expressions share.
- Multiply the factors.
-
Distributive Property
- If , , are real numbers, then
and
- If , , are real numbers, then
-
Factor the greatest common factor from a polynomial.
- Find the GCF of all the terms of the polynomial.
- Rewrite each term as a product using the GCF.
- Use the Distributive Property ‘in reverse’ to factor the expression.
- Check by multiplying the factors.
Section Exercises
Practice Makes Perfect
Find the Greatest Common Factor of Two or More Expressions
In the following exercises, find the greatest common factor.
Solution
15
Solution
25
Solution
4
Solution
5
Solution
3x
Solution
12p3
Solution
2a
Solution
10y
Solution
5x3
Solution
7b2
Factor the Greatest Common Factor from a Polynomial
In the following exercises, factor the greatest common factor from each polynomial.
Solution
5(y + 3)
Solution
4(b − 5)
Solution
7(x − 1)
Solution
3(n2 + 7n + 4)
Solution
6(q2 + 5q + 7)
Solution
c(9c + 22)
Solution
x(17x + 7)
Solution
q(4q + 7)
Solution
3r(r + 9)
Solution
10u(3u − 1)
Solution
b(a + 8)
Solution
11y(5 − y3)
Solution
15c2(3c − 1)
Solution
6c(c2 − d2)
Solution
24x2(2x + 3)
Solution
18a3(8a3 + 5)
Solution
10(y2 + 5y + 4)
Solution
12(u2 − 3u − 9)
Solution
5p2(p2 − 4p − 3)
Solution
8c3(c2 + 5c − 7)
Solution
−7(p + 12)
Solution
−6b(3b + 11)
Solution
−8a2(a − 4)
Solution
−9b3(b2 − 7)
Everyday Math
Revenue A manufacturer of microwave ovens has found that the revenue received from selling microwaves a cost of dollars each is given by the polynomial Factor the greatest common factor from this polynomial.
Height of a baseball The height of a baseball hit with velocity feet/second at feet above ground level is with the number of seconds since it was hit. Factor the greatest common factor from this polynomial.
Solution
−4(4t2 − 20t − 1)
Writing Exercises
The greatest common factor of and is Explain what this means.
What is the GCF of , , and ? Write a general rule that tells how to find the GCF of , , and .
Solution
Answers will vary.
Self Check
ⓐ After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section.

ⓑ Overall, after looking at the checklist, do you think you are well-prepared for the next Chapter? Why or why not?
Chapter Review Exercises
Add and Subtract Polynomials
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.
Solution
trinomial
Solution
binomial
Determine the Degree of Polynomials
In the following exercises, determine the degree of each polynomial.
Solution
2
Solution
0
Add and Subtract Monomials
In the following exercises, add or subtract the monomials.
Solution
15p
Add
Solution
−3n5
Subtract from
Add and Subtract Polynomials
In the following exercises, add or subtract the polynomials.
Solution
10a2 + 4a − 1
Solution
6y2 − 3y + 3
Find the sum of and
Solution
8q3 + q2 + 6q − 29
Find the difference of and
Evaluate a Polynomial for a Given Value of the Variable
In the following exercises, evaluate each polynomial for the given value.
when
Solution
995
when
when
Solution
2,955
when
when
Solution
−163
when
A pair of glasses is dropped off a bridge feet above a river. The polynomial gives the height of the glasses seconds after they were dropped. Find the height of the glasses when
Solution
64 feet
The fuel efficiency (in miles per gallon) of a bus going at a speed of miles per hour is given by the polynomial Find the fuel efficiency when mph.
Use Multiplication Properties of Exponents
Simplify Expressions with Exponents
In the following exercises, simplify.
Solution
216
Solution
0.25
Simplify Expressions Using the Product Property of Exponents
In the following exercises, simplify each expression.
Solution
p13
Solution
a6
Simplify Expressions Using the Power Property of Exponents
In the following exercises, simplify each expression.
Solution
y12
Solution
310
Simplify Expressions Using the Product to a Power Property
In the following exercises, simplify each expression.
Solution
64n2
Solution
256a8b8
Simplify Expressions by Applying Several Properties
In the following exercises, simplify each expression.
Solution
27a15
Solution
x21
Multiply Monomials
In the following exercises, multiply the monomials.
Solution
−54p5
Solution
56x3y11
Multiply Polynomials
Multiply a Polynomial by a Monomial
In the following exercises, multiply.
Solution
70 − 7x
Solution
−625y4 + 5y
Multiply a Binomial by a Binomial
In the following exercises, multiply the binomials using various methods.
Solution
a2 + 7a + 10
Solution
6x2 − 19x − 7
Solution
n2 + 9n + 8
Solution
5u2 + 37u − 24
Solution
p2 + 11p + 28
Solution
27c2 − 3c − 4
Multiply a Trinomial by a Binomial
In the following exercises, multiply using any method.
Solution
x3 − 2x2 − 24x − 21
Solution
m3 − m2 − 72m − 180
Divide Monomials
Simplify Expressions Using the Quotient Property of Exponents
In the following exercises, simplify.
Solution
26 or 64
Solution
Simplify Expressions with Zero Exponents
In the following exercises, simplify.
Solution
1
Solution
1
Simplify Expressions Using the Quotient to a Power Property
In the following exercises, simplify.
Solution
Solution
Simplify Expressions by Applying Several Properties
In the following exercises, simplify.
Solution
a2
Solution
Solution
Divide Monomials
In the following exercises, divide the monomials.
Solution
9p9
Solution
Solution
Solution
Integer Exponents and Scientific Notation
Use the Definition of a Negative Exponent
In the following exercises, simplify.
Solution
Solution
Simplify Expressions with Integer Exponents
In the following exercises, simplify.
Solution
x6
Solution
Solution
k6
Solution
b10
Convert from Decimal Notation to Scientific Notation
In the following exercises, write each number in scientific notation.
Solution
5.3 × 106
The thickness of a piece of paper is about millimeter.
Solution
9.7 × 10−2 millimeter
According to www.cleanair.com, U.S. businesses use about tons of paper per year.
Convert Scientific Notation to Decimal Form
In the following exercises, convert each number to decimal form.
Solution
29,000
Solution
0.375
Multiply and Divide Using Scientific Notation
In the following exercises, multiply and write your answer in decimal form.
Solution
6,000
Solution
30,000,000,000
Introduction to Factoring Polynomials
Find the Greatest Common Factor of Two or More Expressions
In the following exercises, find the greatest common factor.
Solution
5
Solution
4x2
Factor the Greatest Common Factor from a Polynomial
In the following exercises, factor the greatest common factor from each polynomial.
Solution
8(2u − 3)
Solution
6p(p + 1)
Solution
−9a3(a2 + 1)
Solution
5(y2 − 11y + 9)
Chapter Practice Test
For the polynomial
- ⓐ Is it a monomial, binomial, or trinomial?
- ⓑ What is its degree?
Solution
- ⓐ trinomial
- ⓑ 4
In the following exercises, simplify each expression.
Solution
6x2 − 3x + 11
Solution
n5
Solution
−48x5y9
Solution
s2 + 17s + 72
Solution
55a2 − 41a + 6
Solution
24a2 + 34ab − 45b2
Solution
x14
Solution
Solution
3y2 − 7x
Solution
Solution
x9
In the following exercises, factor the greatest common factor from each polynomial.
Solution
−6x(x + 5)
According to www.cleanair.org, the amount of trash generated in the US in one year averages out to pounds of trash per person. Write this number in scientific notation.
Convert to decimal form.
Solution
0.000525
In the following exercises, simplify, and write your answer in decimal form.
Solution
A hiker drops a pebble from a bridge feet above a canyon. The polynomial gives the height of the pebble seconds a after it was dropped. Find the height when









































