1. Evaluate Expressions (XEI301,401) Name Dec 5, 2011 1. Evaluating Expressions Example 1: Evaluate the expression for t = 12 t + 20 I DO (12) + 20 = 32 Example 2: Evaluate the expression for y = 4 4y + 2 4(4) + 2 16 + 2 = 18 ALWAYS SUBSTITUTE VALUE IN PARENTHESES

2. Evaluate Expressions (XEI301,401) Name Dec 5, 2011 1. Evaluating Expressions Example 3: Evaluate the expression for c = -5 c – 14 WE DO (-5) – 14 = -19 Example 4: Evaluate the expression for d = -8 3d + 5 3(-8) + 5 -24 + 5 = -19

3. Evaluate Expressions (XEI301,401) Name Dec 5, 2011 1. Evaluating Expressions Example 5: Evaluate the expression for x = 3 I DO Example 6: Evaluate the expression for z = 3 4z 2 + 2z + 5 4(3) 2 + 2(3) + 5 4*9 + 6 + 5 SUBSTITUTE VALUE IN PARENTHESES Z 2 and Z are NOT LIKE TERMS 36 + 6 + 5 = 47

4. Evaluate Expressions (XEI301,401) Name Dec 5, 2011 1. Evaluating Expressions Example 7: Evaluate the expression for x = -2 WE DO Example 8: Evaluate the expression for z = -4 5z – 2z 2 + 7 5(-4) + -2(-4) 2 + 7 5*-4 + -2*16 + 7 ALWAYS SUBSTITUTE VALUE IN PARENTHESES -20 + -32 + 7 = -45 PLUS NEGATIVE!

5. Evaluate Expressions (XEI301,401) Name Dec 5, 2011 2. Evaluating Expressions with two or more variables Example 9: Evaluate the expression for x=2, y=3, z=5 3x + 5y – 3z WE DO 3(2) + 5(3) + -3(5) 6 + 15 + -15 = 6 Different variables are NOT LIKE TERMS

6. Evaluate Expressions (XEI301,401) Name Dec 5, 2011 2. Evaluating Expressions with two or more variables Example 10: Evaluate the expression for x=2, y=3, z=5 3(x + y) + 7z WE DO 3(2) + 3(3) + 7(5) 6 + 9 + 35 = 50 3x + 3y + 7z First, simplify by distributive property