1. Vocabulary Variable Constant Algebraic Expression Evaluate

2. Vocabulary A variable is a letter or symbol that represents a quantity that can change. A constant is a quantity that does not change. Inflation Table: 19502000 $1$7 $2$14 $3$21 $ p$ p x 7 In the table what are your variables and what are you constants?

3. An algebraic expression contains one or more variables and may contain operation symbols. So p  7 is an algebraic expression. Algebraic Expressions NOT Algebraic Expressions 150 + y85 ÷ 5 35  w + z 10 + 3  5 To evaluate an algebraic expression, substitute a number for the variable and then find the value.

4. You can write multiplication and division expressions without using the symbols  and . Instead of... You can write... x  3 x  3 35 ÷ y x(3) 3x3x 35 y When you are multiplying a number times a variable, the number is written first. Write “3x” not “x3.” Read 3x as “three x.” Writing Math

5. Evaluate the expression to find the missing values in the table. Additional Example 1A: Evaluating Algebraic Expressions Substitute for y in 5  y. y 5  y 16 27 35 80 y = 16; 5  16 = 80 y = 27; 5  = y = 35; 5  =

6. Evaluate the expression to find the missing values in the table. Additional Example 1B: Evaluating Algebraic Expressions z z  5 + 4 2 20 45 60 20 z = 20; 20  5 + 16 = 20 z = 45; __  5 + 16 = __ z = 60; __  5 + 16 = __ Substitute for z in z  5 + 4 2.

7. Check It Out: Example 1A Evaluate the expression to find the missing values in the table. Substitute for x in x  9. x x  9 18 36 54 2 x = 18; 18  9 = 2 x = 36;  9 = x = 54;  9 =