2. Essential Question: How do we Evaluate Algebraic Expressions? (+ & -) U3D4

3. Variable: Is a quantity that can change or vary. Mathematicians use letters to represent variables. Constant: A quantity (number) that does not change. 6 + x Expression: Is a mathematical phrase involving constants, variables, and operation symbols. (no equal signs) Vocabulary

4. Steps to Evaluate Expressions Step 1: Identify the variable. (Letter) x Step 2: Put parentheses around the variable. 6 + (x) Step 3: Plug in the number for the variable. 6 + (3) Step 4: Evaluate (simplify) 6 + 3 is 9 6 + x, When x is 3

5. Evaluate each expression for x=1, 2, and 3. xX + 5 1 2 3 (x) + 5(1) + 56 (x) + 5 (2) + 5 (3) + 5 7 8 Step 1: Identify the variable: X Step 2: Step 3: Step 4: Example 1:

6. y11 – y 3 4 5 Evaluate each expression for y=3, 4, and 5. 11 - (y) 11 - (3)8 11 - (4)7 11 - (5)6 Step 3: Step 1: Identify the variable: y Step 2: Step 4: Example 2:

7. n n – 7 3 4 5 Evaluate each expression for n=3, 4, and 5. (n) - 7 (3) - 7-4 (4) - 7-3 (5) - 7-2 Step 1: Identify the variable: n Step 3: Step 2: Step 4: Example 3:

8. Evaluate each expression x= 3 and 5. 1.X + 2 2. 15-x x=3 X=5 x=5 3.X - 9 4. x + 7 X=3 x=3 X=5 x=5

9. Summary Write an example of: How do we Evaluate Algebraic Expressions? (+ & -)