Pre-Algebra Demystified

Math Note: The distributive property is called the distributive

property for multiplication over addition.

PRACTICE

Multiply each of the following:

1. 6(3xþ8y)


2. 2(bþ4)


3. 4(7a
   2bþ3c)


4. 
   3(2p
   5qþ3r)


5. 
   5(6x
   7yþz)

ANSWERS

1. 18xþ48y


2. 2bþ 8


3. 28a
   8bþ12c


4. 
   6pþ15q
   9r


5. 
   30xþ35y
   5z

Combining Like Terms

Like termshave the same variables and the same exponents of the variables.

For example, 3x and
5x are like terms because they have the same variables,

whereas 5x and
8y areunlike termsbecause they have different variables.

Table 7-1 will help you to identify like terms.

Like terms Unlike terms

2x,
7x


8x^2 ,3x^2

13xy,
7xy

5x^2 y, 3x^2 y

x, 4x

2x,
7y


8x^2 ,3x

13xy,
7xz

5x^2 y, 3xy^2

x, 4

Table 7-1 Identification of like terms

Like terms can be added or subtracted: e.g., 4xþ2x¼6x.

130 CHAPTER 7 Expression and Equations