Section 1.2

Variables, Expressions, and Properties

Variable

• A Variable is a symbol, usually a letter, used to represent a number

4 x n a + 7b

5 + r 3x – 4 * t

t – 2 y – 3 + r

Numerical Expression

• Numerical Expression contains numbers and at least one operation.

Examples:3 + 2 17 * 3

20 / 4

14 – 8 21 - 5 + 21000 / 8 + 123

Algebraic Expression

• An Algebraic Expression contains variables, numbers and at least one operation symbol.

4 x n a + 7b

5 + r 3x – 4 * t

t – 2 y – 3 + r

Which of the following is NOT an Algebraic Expression?

Evaluate an Expression

• To Evaluate an expression means to ‘solve’ the expression.

For example:

Evaluate the following numerical expressions:

1. 3 + 4 2. 12 / 23. 7*6

Evaluate the following algebraic expressions, if a=2 b=5 c=8:

1. a + 13 2. 19 – b3. a * c

1. 2 + 13 2. 19 – 5 3. 2 * 8

• If an expression has more than one operation you must use:

ORDER OF OPERATION

ORDER OF OPERATION

• 1. Evaluate expressions inside grouping symbols. (Parentheses)

• 2. Evaluate all powers. (Exponents)• 3. Do all multiplications and/or divisions from

left to right. (Multiplication and Division)• 4. Do all additions and/or subtractions from

left to right. (Addition and Subtraction)

Please Excuse My Dear Aunt Sally