1. Warm Up 1.3 3 + 7(12 – 4) 2.2. How much will it cost to cut a log into eight pieces if cutting it into four pieces costs $12? 3. Write a verbal phrase to represent the expression of : n + 4. Course 2 83

2. V ARIABLES AND E XPRESSIONS

3. A variable is a placeholder, a letter that represents a number. We often use x and y. Evaluating means substituting a number for a variable, and then solving. Example: 3x – 4y where x = 5, y = 2 3 · 5 - 4 · 2 15 - 8 = 7

4. Evaluate k + 9 for each value of k. A. k = 5 k + 9 5 + 9 14 Substitute 5 for k. Add. B. k = 2 k + 9 2 + 9 Substitute 2 for k. 11 Add.

5. Evaluate the expressions for the given value of the variable. A. 4 x – 3 for x = 2 4(2) – 3 8 – 3 5 Substitute 2 for x. Multiply. Subtract.

6. B. r ÷ 3 + r, for r = 12 12 ÷ 3 + 12 4 + 12 16 C. 4 y 2 + 2 y, for y = 3 4(3) 2 + 2(3) 4(9) + 2(3) 36 + 6 42 Substitute 12 for r. Divide. Add. Substitute 3 for y. Evaluate the power. Multiply. Add.

7. T RANSLATING A LGEBRAIC E XPRESSIONS + plus, sum, more than, increased by, total, in all – minus, difference, less than, subtract, decreased by · times, product, multiplied, each, of ÷ divided, quotient, over, split equally

8. Homework: Pg 16-17 #14-21, 24-30 (evens only here), 43