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

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

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

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

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

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

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

Evaluating Powers (x + y)2 when x = 3 and y = 2 25 x2 + y2 when x = 3 and y = 2 13 2x3 when x = 4 128 (2x)3 when x = 4 512

Practice On white boards

Homework Worksheet – “1-1 Variables and Expressions”