1. 1-1 Variables and expressions
Goals:
Evaluate variable expressions
Evaluate expressions containing exponents

2. Vocabulary Variable – a letter used to represent numbers
Usually x, y or z
Value – the number the variable is representing
If x = 2 then 2 is the value of x.
Algebraic expression – collection of numbers, variables and operations (+,-,*,÷) 2x
3y + 1
5k – 7

3. Variable Expressions 8y 5(x) v ÷ 3 4 + g y – 9 8 times y
Meaning
Operation 8y
5(x)
v ÷ 3
4 + g
y – 9
8 times y
Multiplication
5 times x
Multiplication
6 divided by w
Division
v divided by 3
Division
4 plus g
Addition
y minus 9
Subtraction

4. Evaluating Expressions
Evaluate - replace each variable with a number to find the value of the expression
Examples:
8y when y = 3 24
x + 7 when x = 12 19
3x + 1 when x = 5 16
2x + 5y when x = 4 and y = 8 48

5. Vocabulary
Power – an expression that looks like 46 Exponent – the number of times a number is multiplied by itself Base – The number that is multiplied by itself Square – a number raised to the second power Cube – a number raised to the third power

6. Reading and Writing Powers
Words
Meaning
101 52 43 64 x7
Ten to the first power 10
Five to the second power
Five squared
5 * 5 = 25
Four to the third power
Four cubed
4 * 4 * 4 = 64
Six to the fourth power
6 * 6 * 6 * 6 = 1296
x * x * x * x * x * x * x
x to the seventh power

7. Evaluating Powers
x3 when x = 5
125
y2 when y = 7 49
w5 when w = 2 32

8. Evaluating Powers (x + y)2 when x = 3 and y = 225
x2 + y2 when x = 3 and y = 2 13
2x3 when x = 4
128
(2x)3 when x = 4
512

9. Practice
On white boards

10. Homework
Worksheet – “1-1 Variables and Expressions”