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2.07 Factoring out the greatest common factor (GCF)

Worksheet
Factoring out the greatest common factor (GCF)
1

Find the greatest common factor between each set of terms:

a

3 and 15 x

b

8 a and 9 a

c

33 x and 6 x^{2}

d

12 b and 15 b^{2} x

2

Complete the following statements:

a

4 r + 12 = ⬚ \left(r + 3\right)

b

5 v - 30 = ⬚ \left(v - 6\right)

c

18 c - 24 = ⬚ \left( 3 c - 4\right)

d

2 t^{2} + 2 t = 2 t \left(⬚ + ⬚\right)

3

Factor the following expressions:

a

6 v + 30

b

45 t - 40

c

- 2 s - 10

d

- 12 s + 10

e

y^{2} + 4 y

f

k^{2} - 5 k

g

2 u^{2} - 8 u

h

4 t + 2 t^{2}

i

42 x - x^{2}

j

7 x + 35

k

36 - 6 x

l

- 2 x + 10

m

- 100 - 10 x

n

- 18 y^{2} + 6

o

9 \left( 3 x + 4\right) + 4 \left( 3 x + 4\right)

p

8 t \left(t - 3\right) + 9 \left(t - 3\right)

Additional questions
4

Xander was asked to factor the expression 35x^2y+10xy^2-5xy. Identify his error.

Xander:

The greatest common factor is 5xy so the factored form of the expression is 5xy(7x+2y)

5

A farmer wants to create a set of adjacent fields which all have the same width. He plans to create the smallest field in the shape of a square, with the largest field 9 times the size of the smallest field, and the middle field to have a length that is 5 units more than the smallest field.

a

Write expressions for the area of each field.

b

Use factoring to determine the dimensions of the entire field.

6

Explain how dividing monomials relates to factoring the greatest common factor.

7

Explain why the greatest common factor of the variables in any expression has the least possible exponent of any of the terms.

8

You are to design a photo collage made of two large square photos with a side length of x and four smaller rectangular photos that have a height of x and a width of 4 inches.

a

Find an algebraic expression for the area of the rectangle formed if the photos are all placed in a single row. Draw an example of what this arrangement would look like.

b

Fully factor your answer from part (a) and then draw a photo arrangement that would match these dimensions.

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Outcomes

MA.8.AR.1.3

Rewrite the sum of two algebraic expressions having a common monomial factor as a common factor multiplied by the sum of two algebraic expressions.

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