Prealgebra 2e — Original English

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.

On the left, the equation 8 times 7 equals 56 is shown. 8 and 7 are labeled factors, 56 is labeled product. On the right, the equation 2x times parentheses x plus 3 equals 2 x squared plus 6x is shown. 2x and x plus 3 are labeled factors, 2 x squared plus 6x is labeled product. There is an arrow on top pointing to the right that says “multiply” in red. There is an arrow on the bottom pointing to the left that says “factor” in red.

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 24 and 36.

Solution

Solution

Step 1: Factor each coefficient into primes. Write all variables with exponents in expanded form. Factor 24 and 36. Factor trees demonstrating the prime factorization of 24 and 36.
Step 2: List all factors--matching common factors in a column. Two lines of mathematical equations demonstrating the prime factorization of 24 and 36. 24 is shown as 2 x 2 x 2 x 3, and 36 as 2 x 2 x 3 x 3, with an underline beneath the latter.
In each column, circle the common factors. Circle the 2, 2, and 3 that are shared by both numbers. A step-by-step example of finding the Greatest Common Factor (GCF) of 24 and 36 using prime factorization, illustrating how common prime factors (2, 2, and 3) are multiplied to get the GCF, which is 12.
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, 24 and 36 can be written as multiples of 12.

24=12·236=12·3

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 5xand15.

Solution

Solution

Factor each number into primes.
Circle the common factors in each column.
Bring down the common factors.
An image shows the calculation for the Greatest Common Factor (GCF) of 5x and 15. It factors 5x as 5*x and 15 as 3*5. The common factor '5' is circled, resulting in GCF = 5.
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 12x2 and 18x3.

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.
An algebraic problem illustrating the calculation of the Greatest Common Factor (GCF) for 12x^2 and 18x^3. The image factors both expressions, using pink circles to highlight common factors that combine to form the GCF, 6x^2.
The GCF of12x2and18x3is6x2

Find the greatest common factor of 14x3,8x2,10x.

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.
An image illustrating the process of finding the Greatest Common Factor (GCF) of 14x^3, 8x^2, and 10x. The prime factorization of each term is listed, with common factors (2 and x) circled, leading to a GCF of 2x.
The GCF of14x3and8x2, and10xis2x

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, 12 as 2·6or3·4), 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:

2(x + 7)factors 2·x + 2·7 2x + 14product

Here, we will start with a product, like 2x+14, and end with its factors, 2(x+7). 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: 2x+14.

Solution

Solution

Step 1: Find the GCF of all the terms of the polynomial. Find the GCF of 2x and 14. A math problem demonstrating how to find the Greatest Common Factor (GCF) of 2x and 14. The number 2 is circled as the common factor, yielding GCF = 2.
Step 2: Rewrite each term as a product using the GCF. Rewrite 2x and 14 as products of their GCF, 2.
2x=2x
14=27
A mathematical expression showing the process of factoring out a common number. The first line is 2x + 14, and the second line breaks down 14 into 2 * 7, highlighting the common factor of 2 in red as 2 * x + 2 * 7.
Step 3: Use the Distributive Property 'in reverse' to factor the expression. 2(x+7)
Step 4: Check by multiplying the factors. Check:
An image illustrating the distributive property in algebra, showing the expansion of 2(x+7) into 2x+14. The steps demonstrate multiplying 2 by both x and 7, resulting in 2x + 14, confirmed with a checkmark.

Notice that in Example 5, we used the word factor as both a noun and a verb:

Noun7is a factor of14Verbfactor2from2x+14

Factor: 3a+3.

Solution

Solution

A math problem illustrating how to find the Greatest Common Factor (GCF) of 3a and 3. The solution shows 3a factored as 3 * a and 3 as 3, highlighting 3 as the common factor, resulting in GCF = 3.
The mathematical expression '3a + 3' is displayed in a bold, dark gray font against a plain white background.
Rewrite each term as a product using the GCF. A mathematical expression showing 3 multiplied by 'a' plus 3 multiplied by 1, which can be factored as 3(a+1).
Use the Distributive Property 'in reverse' to factor the GCF. A mathematical expression: 3(a + 1).
Check by multiplying the factors to get the original polynomial.
Illustration of the distributive property, showing 3(a+1) expanding to 3a + 3 with a checkmark for correctness.

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: 12x60.

Solution

Solution

Steps to find the Greatest Common Factor (GCF) of 12x and 60 using prime factorization, showing the common factors circled and the final GCF as 12.
The mathematical expression '12x - 60' is displayed in a dark gray font on a white background.
Rewrite each term as a product using the GCF. The mathematical expression 12 multiplied by x minus 12 multiplied by 5 is shown.
Factor the GCF. A mathematical expression shows twelve multiplied by the quantity x minus five, written as 12(x - 5).
Check by multiplying the factors.
Applying the distributive property to simplify the algebraic expression 12(x-5) step-by-step, resulting in 12x-60.

Now we’ll factor the greatest common factor from a trinomial. We start by finding the GCF of all three terms.

Factor: 3y2+6y+9.

Solution

Solution

Finding the GCF of 3y^2, 6y, and 9 using prime factorization. Each term's factors are listed, and the common factor, 3, is circled, showing GCF = 3.
A mathematical expression displaying 3y squared plus 6y plus 9.
Rewrite each term as a product using the GCF. A mathematical expression displaying 3 multiplied by y squared, plus 3 multiplied by 2y, plus 3 multiplied by 3. The number 3 is highlighted in red in each term of the expression.
Factor the GCF. A mathematical expression showing 3 multiplied by the quantity (y-squared plus 2y plus 3), as 3(y^2 + 2y + 3).
Check by multiplying.
An algebraic expression 3(y^2 + 2y + 3) is expanded using the distributive property, showing the steps to arrive at the simplified form 3y^2 + 6y + 9, which is marked as correct.

In the next example, we factor a variable from a binomial.

Factor: 6x2+5x.

Solution

Solution

6x2+5x
Find the GCF of 6x2 and 5x and the math that goes with it. This image illustrates the process of finding the Greatest Common Factor (GCF) of 6x^2 and 5x by factoring. The common factor 'x' is highlighted, leading to a GCF of x.
Rewrite each term as a product. A mathematical expression showing 'x times 6x plus x times 5'. The variable 'x' is highlighted in red for both instances, emphasizing its presence in the terms.
Factor the GCF. x(6x+5)
Check by multiplying.
x(6x+5)
x6x+x5
6x2+5x

When there are several common factors, as we’ll see in the next two examples, good organization and neat work helps!

Factor: 4x320x2.

Solution

Solution

An algebraic example showing how to find the Greatest Common Factor (GCF) of 4x^3 and 20x^2. Prime factors are listed and common factors are circled in pink, resulting in a GCF of 4x^2.
A mathematical expression reads 4x^3 - 20x^2 in black text on a white background, formatted with standard mathematical notation for exponents and subtraction.
Rewrite each term. The mathematical expression '4x^2 * x - 4x^2 * 5' is displayed, showing a subtraction operation between two terms, both involving 4x^2 multiplied by another factor.
Factor the GCF. The image displays the algebraic expression 4x^2(x-5) in black text on a white background, representing a polynomial in factored form. The terms are clearly visible, indicating multiplication.
Check. Algebraic expansion of 4x^2(x-5) to 4x^3 - 20x^2, illustrating the distributive property applied correctly and step-by-step.

Factor: 21y2+35y.

Solution

Solution

Find the GCF of 21y2 and 35y Finding the Greatest Common Factor (GCF) of 21y^2 and 35y. The image demonstrates the prime factorization of both terms, highlighting common factors (7 and y) to calculate the GCF, which is 7y.
The image displays the mathematical expression '21y^2 + 35y' in black text against a white background.
Rewrite each term. A mathematical expression displaying the equation 7y multiplied by 3y, added to 7y multiplied by 5, with '7y' highlighted in red.
Factor the GCF. A mathematical expression showing the term 7y multiplied by the binomial (3y + 5).

Factor: 14x3+8x210x.

Solution

Solution

Previously, we found the GCF of 14x3,8x2,and10x to be 2x.

14x3+8x210x
Rewrite each term using the GCF, 2x. A mathematical expression: 2x * 7x^2 + 2x * 4x - 2x * 5, showing a common factor of '2x' highlighted in red across three terms for potential factoring.
Factor the GCF. 2x(7x2+4x5)
Algebraic check using the distributive property: 2x(7x^2 + 4x - 5) = 2x*7x^2 + 2x*4x - 2x*5 = 14x^3 + 8x^2 - 10x, confirmed with a checkmark.

When the leading coefficient, the coefficient of the first term, is negative, we factor the negative out as part of the GCF.

Factor: −9y27.

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. The image demonstrates finding the Greatest Common Factor (GCF) of 9y and 27. It shows the prime factorization of 9y as 3*3*y and 27 as 3*3*3, with common factors 3 and 3 circled. The GCF is calculated as 9.
Since the expression −9y−27 has a negative leading coefficient, we use −9 as the GCF.
9y 27
Rewrite each term using the GCF. The image shows the mathematical expression -9 * y + (-9) * 3, which demonstrates the distributive property in an algebraic context. The number -9 is a common factor in both terms of the expression.
Factor the GCF. 9(y+3)
A mathematical check demonstrates the distributive property, simplifying -9(y + 3) to -9y - 27, confirmed correct with a checkmark.

Pay close attention to the signs of the terms in the next example.

Factor: −4a2+16a.

Solution

Solution

The leading coefficient is negative, so the GCF will be negative.
The Greatest Common Factor (GCF) of 4a^2 and 16a is determined by prime factorization. Common factors (2, 2, a) are circled, and their product yields the GCF, which is 4a.
Since the leading coefficient is negative, the GCF is negative, −4a.
−4a2+16a
Rewrite each term. -4a * a - (-4a) * 4
Factor the GCF. 4a(a4)
Check on your own by multiplying.

Key Concepts

  • Find the greatest common factor.
    1. Factor each coefficient into primes. Write all variables with exponents in expanded form.
    2. List all factors—matching common factors in a column. In each column, circle the common factors.
    3. Bring down the common factors that all expressions share.
    4. Multiply the factors.
  • Distributive Property
    • If a, b, c are real numbers, then
      a(b+c)=ab+ac and ab+ac=a(b+c)
  • Factor the greatest common factor from a polynomial.
    1. Find the GCF of all the terms of the polynomial.
    2. Rewrite each term as a product using the GCF.
    3. Use the Distributive Property ‘in reverse’ to factor the expression.
    4. 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.

40,56

45,75

Solution

15

72,162

150,275

Solution

25

3x,12

4y,28

Solution

4

10a,50

5b,30

Solution

5

16y,24y2

9x,15x2

Solution

3x

18m3,36m2

12p4,48p3

Solution

12p3

10x,25x2,15x3

18a,6a2,22a3

Solution

2a

24u,6u2,30u3

40y,10y2,90y3

Solution

10y

15a4,9a5,21a6

35x3,10x4,5x5

Solution

5x3

27y2,45y3,9y4

14b2,35b3,63b4

Solution

7b2

Factor the Greatest Common Factor from a Polynomial

In the following exercises, factor the greatest common factor from each polynomial.

2x+8

5y+15

Solution

5(y + 3)

3a24

4b20

Solution

4(b − 5)

9y9

7x7

Solution

7(x − 1)

5m2+20m+35

3n2+21n+12

Solution

3(n2 + 7n + 4)

8p2+32p+48

6q2+30q+42

Solution

6(q2 + 5q + 7)

8q2+15q

9c2+22c

Solution

c(9c + 22)

13k2+5k

17x2+7x

Solution

x(17x + 7)

5c2+9c

4q2+7q

Solution

q(4q + 7)

5p2+25p

3r2+27r

Solution

3r(r + 9)

24q212q

30u210u

Solution

10u(3u − 1)

yz+4z

ab+8b

Solution

b(a + 8)

60x6x3

55y11y4

Solution

11y(5 − y3)

48r412r3

45c315c2

Solution

15c2(3c − 1)

4a34ab2

6c36cd2

Solution

6c(c2d2)

30u3+80u2

48x3+72x2

Solution

24x2(2x + 3)

120y6+48y4

144a6+90a3

Solution

18a3(8a3 + 5)

4q2+24q+28

10y2+50y+40

Solution

10(y2 + 5y + 4)

15z230z90

12u236u108

Solution

12(u2 − 3u − 9)

3a424a3+18a2

5p420p315p2

Solution

5p2(p2 − 4p − 3)

11x6+44x5121x4

8c5+40c456c3

Solution

8c3(c2 + 5c − 7)

−3n24

−7p84

Solution

−7(p + 12)

−15a240a

−18b266b

Solution

−6b(3b + 11)

−10y3+60y2

−8a3+32a2

Solution

−8a2(a − 4)

−4u5+56u3

−9b5+63b3

Solution

−9b3(b2 − 7)

Everyday Math

Revenue A manufacturer of microwave ovens has found that the revenue received from selling microwaves a cost of p dollars each is given by the polynomial −5p2+150p. Factor the greatest common factor from this polynomial.

Height of a baseball The height of a baseball hit with velocity 80 feet/second at 4 feet above ground level is −16t2+80t+4, with t= 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 36 and 60 is 12. Explain what this means.

What is the GCF of y4, y5, and y10? Write a general rule that tells how to find the GCF of ya, yb, and yc.

Solution

Answers will vary.

Self Check

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

A self-assessment table for math skills, with columns for 'Confidently,' 'With some help,' and 'No-I don't get it!' The skills listed are finding the greatest common factor and factoring it from a polynomial.

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.

y2+8y20

Solution

trinomial

−6a4

9x31

Solution

binomial

n33n2+3n1

Determine the Degree of Polynomials

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

16x240x25

Solution

2

5m+9

−15

Solution

0

y2+6y3+9y4

Add and Subtract Monomials

In the following exercises, add or subtract the monomials.

4p+11p

Solution

15p

−8y35y3

Add 4n5,n5,−6n5

Solution

−3n5

Subtract 10x2 from 3x2

Add and Subtract Polynomials

In the following exercises, add or subtract the polynomials.

(4a2+9a11)+(6a25a+10)

Solution

10a2 + 4a − 1

(8m2+12m5)(2m27m1)

(y23y+12)+(5y29)

Solution

6y2 − 3y + 3

(5u2+8u)(4u7)

Find the sum of 8q327 and q2+6q2

Solution

8q3 + q2 + 6q − 29

Find the difference of x2+6x+8 and x28x+15

Evaluate a Polynomial for a Given Value of the Variable

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

200x15x2 when x=5

Solution

995

200x15x2 when x=0

200x15x2 when x=15

Solution

2,955

5+40x12x2 when x=10

5+40x12x2 when x=−4

Solution

−163

5+40x12x2 when x=0

A pair of glasses is dropped off a bridge 640 feet above a river. The polynomial −16t2+640 gives the height of the glasses t seconds after they were dropped. Find the height of the glasses when t=6.

Solution

64 feet

The fuel efficiency (in miles per gallon) of a bus going at a speed of x miles per hour is given by the polynomial 1160x2+12x. Find the fuel efficiency when x=20 mph.

Use Multiplication Properties of Exponents

Simplify Expressions with Exponents

In the following exercises, simplify.

63

Solution

216

(12)4

(−0.5)2

Solution

0.25

32

Simplify Expressions Using the Product Property of Exponents

In the following exercises, simplify each expression.

p3·p10

Solution

p13

2·26

a·a2·a3

Solution

a6

x·x8

Simplify Expressions Using the Power Property of Exponents

In the following exercises, simplify each expression.

(y4)3

Solution

y12

(r3)2

(32)5

Solution

310

(a10)y

Simplify Expressions Using the Product to a Power Property

In the following exercises, simplify each expression.

(8n)2

Solution

64n2

(−5x)3

(2ab)8

Solution

256a8b8

(−10mnp)4

Simplify Expressions by Applying Several Properties

In the following exercises, simplify each expression.

(3a5)3

Solution

27a15

(4y)2(8y)

(x3)5(x2)3

Solution

x21

(5st2)3(2s3t4)2

Multiply Monomials

In the following exercises, multiply the monomials.

(−6p4)(9p)

Solution

−54p5

(13c2)(30c8)

(8x2y5)(7xy6)

Solution

56x3y11

(23m3n6)(16m4n4)

Multiply Polynomials

Multiply a Polynomial by a Monomial

In the following exercises, multiply.

7(10x)

Solution

70 − 7x

a2(a29a36)

−5y(125y31)

Solution

−625y4 + 5y

(4n5)(2n3)

Multiply a Binomial by a Binomial

In the following exercises, multiply the binomials using various methods.

(a+5)(a+2)

Solution

a2 + 7a + 10

(y4)(y+12)

(3x+1)(2x7)

Solution

6x2 − 19x − 7

(6p11)(3p10)

(n+8)(n+1)

Solution

n2 + 9n + 8

(k+6)(k9)

(5u3)(u+8)

Solution

5u2 + 37u − 24

(2y9)(5y7)

(p+4)(p+7)

Solution

p2 + 11p + 28

(x8)(x+9)

(3c+1)(9c4)

Solution

27c2 − 3c − 4

(10a1)(3a3)

Multiply a Trinomial by a Binomial

In the following exercises, multiply using any method.

(x+1)(x23x21)

Solution

x3 − 2x2 − 24x − 21

(5b2)(3b2+b9)

(m+6)(m27m30)

Solution

m3m2 − 72m − 180

(4y1)(6y212y+5)

Divide Monomials

Simplify Expressions Using the Quotient Property of Exponents

In the following exercises, simplify.

2822

Solution

26 or 64

a6a

n3n12

Solution

1n9

xx5

Simplify Expressions with Zero Exponents

In the following exercises, simplify.

30

Solution

1

y0

(14t)0

Solution

1

12a015b0

Simplify Expressions Using the Quotient to a Power Property

In the following exercises, simplify.

(35)2

Solution

925

(x2)5

(5mn)3

Solution

125m3n3

(s10t)2

Simplify Expressions by Applying Several Properties

In the following exercises, simplify.

(a3)2a4

Solution

a2

u3u2·u4

(xx9)5

Solution

1x40

(p4·p5p3)2

(n5)3(n2)8

Solution

1n

(5s24t)3

Divide Monomials

In the following exercises, divide the monomials.

72p12÷8p3

Solution

9p9

−26a8÷(2a2)

45y6−15y10

Solution

3y4

−30x8−36x9

28a9b7a4b3

Solution

4a5b2

11u6v355u2v8

(5m9n3)(8m3n2)(10mn4)(m2n5)

Solution

4m9n4

42r2s46rs354rs29s

Integer Exponents and Scientific Notation

Use the Definition of a Negative Exponent

In the following exercises, simplify.

6−2

Solution

136

(−10)−3

5·2−4

Solution

516

(8n)−1

Simplify Expressions with Integer Exponents

In the following exercises, simplify.

x−3·x9

Solution

x6

r−5·r−4

(uv−3)(u−4v−2)

Solution

1u3v5

(m5)−1

(k−2)−3

Solution

k6

q4q20

b8b−2

Solution

b10

n−3n−5

Convert from Decimal Notation to Scientific Notation

In the following exercises, write each number in scientific notation.

5,300,000

Solution

5.3 × 106

0.00814

The thickness of a piece of paper is about 0.097 millimeter.

Solution

9.7 × 10−2 millimeter

According to www.cleanair.com, U.S. businesses use about 21,000,000 tons of paper per year.

Convert Scientific Notation to Decimal Form

In the following exercises, convert each number to decimal form.

2.9×104

Solution

29,000

1.5×108

3.75×10−1

Solution

0.375

9.413×10−5

Multiply and Divide Using Scientific Notation

In the following exercises, multiply and write your answer in decimal form.

(3×107)(2×10−4)

Solution

6,000

(1.5×10−3)(4.8×10−1)

6×1092×10−1

Solution

30,000,000,000

9×10−31×10−6

Introduction to Factoring Polynomials

Find the Greatest Common Factor of Two or More Expressions

In the following exercises, find the greatest common factor.

5n,45

Solution

5

8a,72

12x2,20x3,36x4

Solution

4x2

9y4,21y5,15y6

Factor the Greatest Common Factor from a Polynomial

In the following exercises, factor the greatest common factor from each polynomial.

16u24

Solution

8(2u − 3)

15r+35

6p2+6p

Solution

6p(p + 1)

10c210c

−9a59a3

Solution

−9a3(a2 + 1)

−7x828x3

5y255y+45

Solution

5(y2 − 11y + 9)

2q516q3+30q2

Chapter Practice Test

For the polynomial 8y43y2+1

  1. Is it a monomial, binomial, or trinomial?
  2. What is its degree?
Solution
  1. trinomial
  2. 4

In the following exercises, simplify each expression.

(5a2+2a12)+(9a2+8a4)

(10x23x+5)(4x26)

Solution

6x2 − 3x + 11

(34)3

n·n4

Solution

n5

(10p3q5)2

(8xy3)(−6x4y6)

Solution

−48x5y9

4u(u29u+1)

(s+8)(s+9)

Solution

s2 + 17s + 72

(m+3)(7m2)

(11a6)(5a1)

Solution

55a2 − 41a + 6

(n8)(n24n+11)

(4a+9b)(6a5b)

Solution

24a2 + 34ab − 45b2

5658

(x3·x9x5)2

Solution

x14

(47a18b23c5)0

24r3s6r2s7

Solution

4rs6

8y216y+204y

(15xy335x2y)÷5xy

Solution

3y2 − 7x

4−1

(2y)−3

Solution

18y3

p−3·p−8

x4x−5

Solution

x9

In the following exercises, factor the greatest common factor from each polynomial.

80a3+120a2+40a

−6x230x

Solution

−6x(x + 5)

According to www.cleanair.org, the amount of trash generated in the US in one year averages out to 112,000 pounds of trash per person. Write this number in scientific notation.

Convert 5.25×10−4 to decimal form.

Solution

0.000525

In the following exercises, simplify, and write your answer in decimal form.

(2.4×108)(2×10−5)

9×1043×10−1

Solution

300,000

A hiker drops a pebble from a bridge 240 feet above a canyon. The polynomial −16t2+240 gives the height of the pebble t seconds a after it was dropped. Find the height when t=3.

greatest common factor
The greatest common factor (GCF) of two or more expressions is the largest expression that is a factor of all the expressions.