# Order of Operations - Crestwood High School Objective The student will be able to: use the order of operations to evaluate expressions. Indicators NS3 & NS6 Designed by Skip Tyler, Varina High School Edited by Eddie Judd, Crestwood Middle School Evaluate 7 + 4 3. Is your answer 33 or 19? You can get 2 different answers depending on which operation you did first. We want everyone to get

the same answer so we must follow the order of operations. Remember the phrase Please Excuse My Dear Aunt Sally or PEMDAS. ORDER OF OPERATIONS 1. 2. 3. 4.

PE Parentheses - ( ) or [ ] MD Exponents or Powers AS Multiply and Divide (from left to right) Add and Subtract (from left to right) Once again, evaluate 7 + 4 3 and use the order of operations. = 7 + 12 (Multiply.) = 19

(Add.) Example #1 =1 14 7 2 - 3 = 2 2 - 3 (Divide l/r.) = 4 - 3 (Multiply.) (Subtract.) Example #2 3(3 + 7) 2 5

= 3(10) 2 5 (parentheses) = 3(100) 5 (exponents) = 300 5 (multiplication) = 60 (division) Example #3 20 - 3 6 + 102 + (6 + 1) 4 = 20 - 3 6 + 102 + (7) 4 (parentheses)

= 20 - 3 6 + 100 + (7) 4 (exponents) = 20 - 18 + 100 + (7) 4 (Multiply l/r.) = 20 - 18 + 100 + 28 (Multiply l/r.) = 2 + 100 + 28 (Subtract l/r.) = 102 + 28 (Add l/r.) = 130 (Add.) Which of the following represents

112 + 18 - 33 5 in simplified form? 1. 2. 3. 4. -3,236 4 107 16,996 Answer Now Simplify

16 - 2(10 - 3) 1. 2. 3. 4. 2 -7 12 98 Answer Now Simplify

24 6 4 2 1. 2. 3. 4. 72 36 12 0 Answer Now Evaluating a Variable Expression

To evaluate a variable expression: 1. substitute the given numbers for each variable. 2. use order of operations to solve. Example # 4 n + (13 - n) 5 for n = 8 = 8 + (13 - 8) 5 (Substitute.)

= 8+55 (parentheses) = 8+1 (Divide l/r.) = 9 (Add l/r.)

Example # 5 8y - 3x2 + 2n for x = 5, y = 2, n =3 = 8 2 - 3 52 + 2 3 (Substitute.) = 8 2 - 3 25 + 2 3 (exponents) = 16 - 3 25 + 2 3 (Multiply l/r.) = 16 - 75 + 2 3 = 16 - 75 + 6

= -59 + 6 = -53 (Multiply l/r.) (Multiply l/r.) (Subtract l/r.) (Add l/r.) What is the value of -10 4x if x = -13? 1. 2. 3.

4. -62 -42 42 52 Answer Now What is the value of 5k3 if k = -4? 1. 2. 3.

4. -8000 -320 -60 320 Answer Now 2n m What is the value of t if n = -8, m = 4, and t = 2 ?

1. 2. 3. 4. 10 -10 -6 6 Answer Now