Lesson 1 Introductory Algebra The Four Operations WarmUp

Lesson 1 Introductory Algebra The Four Operations

Warm-Up 1. 6× 7 2. 56 ÷ 8 3. 6. 8 + 9. 3 4. 114 – 96

The Four Operations Target: Find values of expressions involving addition, subtraction, multiplication and division.

Vocabulary � Numerical Expression: Combinations of numbers and operations. � Order of Operations: Rules to follow when evaluating an expression with more than one operation.

Order of Operations 1. Multiply and divide from left to right. 2. Add and subtract from left to right.

Example 1 Find the value of 5 × 8 – 12 ÷ 3. � Multiply and divide first. 5 × 8 – 12 ÷ 3 = 40 – 4 � Subtract. 40 – 4 = 36

Example 2 � Find the value of 20 + 16 ÷ 4 – 2 × 9. � Multiply and divide first. 20 + 16 ÷ 4 – 2 × 9 = 20 + 4 – 18 � Add and subtract left to right. 20 + 4 – 18 = 24 – 18 = 6

Example 3 Saul’s mom and dad took him to a basketball game for his birthday. He was allowed to bring four friends with him. His parents bought $24 tickets for each of the five boys so they could sit close to the court. The parents’ tickets cost $10 each. Find the total cost of the game tickets. � Write the problem. $24 × 5 + $10 × 2 � Multiply first. $24 × 5 + $10 × 2 = $120 + $20 � Add. $120 + $20 = $140 � It will cost $140 for the group to go to the game.

Exit Problems 1. 6+9÷ 3– 1 2. 4× 5– 2× 3 3. 8. 8 ÷ 2 + 2. 4

Communication Prompt Why do you think mathematicians developed an order of operations for us to follow?