1. Holt CA Course 1 Evaluating Algebraic Expressions 1-5 AF1.2 Write and evaluate an algebraic expression for a given situation, using up to three variables. Also covered: AF1.3 California Standards

2. Holt CA Course 1 Evaluating Algebraic Expressions 1-5 Vocabulary variable constant A letter that represents a number that can vary. A number that cannot change.

3. Holt CA Course 1 Evaluating Algebraic Expressions 1-5 The expression b + 9 represents Chad’s age when his brother is b years old. Evaluate the expression for each value of b, and then tell what the value of the expression means. Example 1A: Evaluating Algebraic Expressions b = 5 b + 9 5 + 9 14 Substitute 5 for b. Add. When his brother is 5, Chad is 14.

4. Holt CA Course 1 Evaluating Algebraic Expressions 1-5 Example 1B: Evaluating Algebraic Expressions b = 2 b + 9 2 + 9 11 Substitute 2 for b. Add. When his brother is 2, Chad is 11.

5. Holt CA Course 1 Evaluating Algebraic Expressions 1-5 The expression y + 7 represents Sidney’s age when her brother is y years old. Evaluate the expression for each value of y, and then tell what the value of the expression means. Check It Out! Example 1A y = 4 y + 7 4 + 7 11 Substitute 4 for y. Add. When her brother is 4, Sidney is 11.

6. Holt CA Course 1 Evaluating Algebraic Expressions 1-5 Multiplication and division of variables can be written in several ways, as shown in the table. When evaluating expressions, use the order of operations.

7. Holt CA Course 1 Evaluating Algebraic Expressions 1-5 Evaluate the expression for the given value of the variable. Example 2: Evaluating Algebraic Expressions Involving Order of Operations A. 4x – 3 for x = 2 4(2) – 3 8 – 3 5 Substitute 2 for x. Multiply. Subtract.

8. Holt CA Course 1 Evaluating Algebraic Expressions 1-5 Example 2: Evaluating Algebraic Expressions Involving Order of Operations B. s ÷ 5 + s, for s = 15 15 ÷ 5 + 15 3 + 15 18 Substitute 15 for s. Divide. Add.

9. Holt CA Course 1 Evaluating Algebraic Expressions 1-5 Check It Out! Example 2 Evaluate the expression for the given value of the variable. A. 3x – 2 for x = 3 3(3) – 2 9 – 2 7 Substitute 3 for x. Multiply. Subtract.

10. Holt CA Course 1 Evaluating Algebraic Expressions 1-5 Evaluate Example 3: Evaluating Algebraic Expressions with More than One Variable 6a6a + 4b − c, for a = 3, b = 2, and c = 7. 6a6a + 4b − c 6363 + 4(2) − 7 2 + 8 − 7 3 Substitute 3 for a, 2 for b, and 7 for c. Divide and multiply from left to right. Add and subtract from left to right.

11. Holt CA Course 1 Evaluating Algebraic Expressions 1-5 y = 8 y + 7 8 + 7 15 Substitute 8 for y. Add. When her brother is 8, Sidney is 15. The expression y + 7 represents Sidney’s age when her brother is y years old. Evaluate the expression for each value of y, and then tell what the value of the expression means. Check It Out! Example 1

12. Holt CA Course 1 Evaluating Algebraic Expressions 1-5 Check It Out! Example 2 Evaluate the expression for the given value of the variable. 4y 2 + 2y, for y = 3 4(3) 2 + 2(3) 4(9) + 2(3) 36 + 6 42 Substitute 3 for y. Evaluate the power. Multiply. Add.