Expressions

You are familiar with the following type of numerical expressions:

12 + 6

3 (12)

6 (3 + 2)

15 - 4 (6)

What is a variable?

In the expression 12 + B, the letter “B” is a variable.

A A variablevariable is a letter or symbol that is a letter or symbol that represents an unknown value.represents an unknown value.

What are coefficients?A coefficient is the number multiplied by the

variable in an algebraic expression.

Algebraic Expression Coefficient

6m + 5 6

8r + 7m + 4 8, 7

14b - 8 14

Algebraic Expressions

When variables are used with other numbers, parentheses, or operations, they create an

algebraic expression.

a + 2

(a) (b)

3m + 6n - 6

What is a term?

A term is the name given to a number, a variable, or a number and a variable combined

by multiplication or division.

Algebraic Expressions Terms

a + 2 a, 2

3m + 6n - 6 3m, 6n, - 6

What are constants?

• A constant is a number that cannot change its value.

In the expression: 5x + 7y - 2

the constant is - 2.

Evaluation

• Evaluate an algebraic expression – To find the value of an algebraic expression by substituting numbers for variables.

• m + 8 m = 2 2 + 8 = 10• r – 3 r = 5 5 – 3 = 2

Definitions

• Simplify – Combine like terms and complete all operations

m = 2

• m + 8 + m 2 m + 8

• (2 x 2) + 8 4 + 8 = 12

Write Algebraic Expressionsfor These Word Phrases

• A number s plus 2

• A number decrease by 1

• 31 less than a number

• A number b increased by 7

• The sum of a number & 6

• 9 more than a number

s + 2

k - 1

x - 31

b + 7n + 6

z + 9

Evaluate each algebraic expression when x = 10

• x + 8

• x + 49

• x + x

• x - x

• x - 7

• 42 - x

1859

20

03

32

Complete This Table

x x + 65

102132

11162738

Write an Algebraic Expression for These Situations

• Scott’s brother is 2 years younger than Scott

• The sum of two numbers is 12

• The difference between two numbers is 5

s - 2

v + c = 12

m – n = 5