Course Variables and Algebraic Expressions 1-7 Variables and Algebraic Expressions Course 2 Warm Up Warm Up Problem of the Day Problem of the Day Lesson Presentation Lesson Presentation

Course Variables and Algebraic Expressions Warm Up Evaluate. 1. 5(7) – (18 – 11)  (40 – 35) (12 – 4)

Course Variables and Algebraic Expressions Problem of the Day If charged per cut, how much will it cost to cut a log into eight pieces if cutting it into four pieces costs $12? $28

Course Variables and Algebraic Expressions Learn to evaluate algebraic expressions.

Course Variables and Algebraic Expressions Vocabulary variable constant algebraic expression evaluate

Course Variables and Algebraic Expressions Ron Howard was born in You can find out what year Ron turned 16 by adding the year he was born to his age In algebra, letters are often used to represent numbers. You can use a letter such as a to represent Ron Howard’s age. When he turns a years old, the year will be a.

Course Variables and Algebraic Expressions The letter a has a value that can change, or vary. When a letter represents a number that can vary, it is called a variable. The year 1954 is a constant because the number cannot change. An algebraic expression consists of one or more variables. It usually contains constants and operations. For example, a is an algebraic expression for the year Ron Howard turns a certain age.

Course Variables and Algebraic Expressions To evaluate an algebraic expression, substitute a number for the variable. AgeYear born + age = year at age a a

Course Variables and Algebraic Expressions Evaluate k + 9 for each value of k. Additional Example 1: Evaluating Algebraic Expressions A. k = 5 k Substitute 5 for k. Add. B. k = 2 k Substitute 2 for k. 11 Add.

Course Variables and Algebraic Expressions Check It Out: Example 1 Evaluate a + 6 for each value of a. A. a = 3 a Substitute 3 for a. Add. B. a = 5 a Substitute 5 for a. 11 Add.

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

Course Variables and Algebraic Expressions Evaluate the expression for the given value of the variable. Additional 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.

Course Variables and Algebraic Expressions Additional Example 2: Evaluating Algebraic Expressions Involving Order of Operations B. s ÷ 5 + s, for s = ÷ C. 5x 2 + 3x, for x = 2 5(2) 2 + 3(2) 5(4) + 3(2) Substitute 15 for s. Divide. Add. Substitute 2 for x. Evaluate the power. Multiply. Add.

Course Variables and Algebraic Expressions Check It Out: Example 2A 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.

Course Variables and Algebraic Expressions Check It Out: Example 2 B. r ÷ 3 + r, for r = ÷ C. 4y 2 + 2y, 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.

Course Variables and Algebraic Expressions Evaluate Additional Example 3: Evaluating Algebraic Expressions with Two Variables 6a6a + 4b, for a = 3 and b = 2. 6a6a + 4b (2) Substitute 3 for a and 2 for b. Divide and multiply from left to right. Add.

Course Variables and Algebraic Expressions Check It Out: Example 3 Evaluate 8w8w + 2x, for w = 4 and x = 2. 8w8w + 2x (2) Substitute 4 for w and 2 for x. Divide and multiply from left to right. Add.

Course Variables and Algebraic Expressions Lesson Quiz Evaluate n + 7 for each value of n. 1. n = n =31 Evaluate each algebraic expression for the given value of the variables 3. 6y – 5 for y = x 2 + 3x for x = y for x = 4 and y = 3 6. The expression 7d gives the number of days in d weeks. Evaluate 7d for d = 12. How many days are in 12 weeks? x 23 84