Variables and Algebraic Expressions 1 3 Vocabulary Variable

* Variables and Algebraic Expressions 1 -3

Vocabulary Variable- a letter represents a number that can vary. Constant- a number that does not change. Algebraic expression- consists of one or more variables. It usually contains constants and operations. Evaluate- means to substitute a number for the variable.

Additional Example 1: Evaluating Algebraic Expressions Evaluate k + 9 for each value of k. A. k = 5 k+9 5+9 14 B. k = 2 Substitute 5 for k. Add. k+9 Substitute 2 for k. Add.

Check It Out: Example 1 Evaluate a + 6 for each value of a. Solve on your own. A. a = 3 B. a = 5

Multiplication and division of variables can be written in several ways, as shown in the table. When evaluating expressions, use the order of operations.

Additional Example 2: Evaluating Algebraic Expressions Involving Order of Operations Evaluate the expression 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.

Additional Example 2: Evaluating Algebraic Expressions Involving Order of Operations (Solve using the directions given. ) B. s ÷ 5 + s, for s = 15 Substitute 15 for s. Divide. Add. C. 5 x 2 + 3 x, for x = 2 Substitute 2 for x. Evaluate the power. Multiply. Add.

Check It Out: Example 2 A (Solve on your own) Evaluate the expression for the given value of the variable. A. 3 x – 2 for x = 3

Additional Example 3: Evaluating Algebraic Expressions with Two Variables Evaluate 6 a + 4 b, for a = 3 and b = 2. 6 a + 4 b 6 3 + 4(2) 2+8 10 Substitute 3 for a and 2 for b. Divide and multiply from left to right. Add.

Check It Out: Example 3 (Solve on your own. ) Evaluate 8 w + 2 x, for w = 4 and x = 2.