Order Of Operations

1. AIM: How do we properly evaluate expressions using the order of operations ? OBJECTIVE: S.W.B.A.T. use the order of operations to properly evaluate expressions Homework: Basics of Algebra – Day 1: 1 - 18 Also extra credit worksheet available at http://www.schoolrack.com/Ikhaanahoyo September 11, 2007 DO NOW Evaluate 70 - 2(5+3). Evaluate means simplify or “find the answer”

2. Debrief of “Do Now” 70 - 2(5+3) 70 - 2(8) 68(8) 70 - 2(5+3) 70 - 2( 8) 70 – 16 544 incorrect 54 correct Subtraction was done before multiplication Multiplication was done before subtraction The parenthesis here means multiplication !

3. The Order of Operations In math an answer is always right or wrong so we have to have a way of letting people know which operation to do in which order so that everyone gets the same answer. This order is called the Order of Operations G raciously E xcuse M y D ear A unt S ally

4. The Order of Operations Grouping Symbols , Exponents , ( Multiplication/Division ), then ( Add/Subtract ) Grouping Symbols 3 2 Exponents 9 ∙4÷2 = 18 Multiplication/Division from left to right 7 – 4 + 2 = 5 Add/Subtract from left to right [],{}, fraction bar , (),

5. The Order of Operations – Example 1 Evaluate 15 ÷ 5 – 3 ∙ 2 A method that has been very successful for working with order of operations is the GEMDAS table. 3 – 3 ∙ 2 3 – 6 -3

6. 10 ÷ (2 2 + 1) The Order of Operations – Example 2 10 ÷ (4 + 1) When you enter grouping symbols GEMDAS starts all over again so the exponents go first! 10 ÷ 5 2

7. Warning!!! No calculators on next quiz !

8. The Order of Operations – Example 3 Evaluate the expression 5 – 3 + 7 ∙ 2 5 – 3 + 14 2 + 14 Why does subtraction come before addition ? 16

9. The Order of Operations – Groupwork 1, 4, 15