Warm Up (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

V ARIABLES AND E XPRESSIONS

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 · · = 7

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

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.

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

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

Homework: Pg #14-21, (evens only here), 43