Multiplication and Division of Integers

Cornell Notes objective I will add integers… Origin 9/11/06 Notes The point on the line labeled zero Summary or questions

Hey- your idea was great! Share out… If your partner had an idea about multiplying or dividing with negative numbers, please share their thought. Hey- your idea was great!

Here’s a way I can Remember! To remember whether your answer will be positive or negative when MULTIPLYING or DIVIDING, we’ll use: Mr. Multiplivision

= -15 What sign is left uncovered? When multiplying Integers, cover the Two signs you are using Choral Response What sign is left uncovered? Ex.: 5 (-3) Negative, - That is the sign of The answer = -15

Practice … under time! (-10)(3) = 21  -5 = -13  -6 = (raffle tickets…) (-10)(3) = 21  -5 = -13  -6 =

1:00

Division It’s not any different! Good News: Ex.: -48  (-4) = + 12

Reminder: Equal means it works both ways! 

“Boss” and “Secretary” Person B: Boss first Partner A: Secretary first Tell the “secretary” what to write in solving Copy exactly what boss says Turn to your neighbor: Person on the left: what’s good about this Right: What’s the bad consequence of this Response: They can copy notes, vocab, etc. while holding another conversation, thinking about the weekend, etc. Cornell notes: questions, summaries Frayer model- student worded definition Good News + It”s easy to get their attention with ANY thing different Think Pair Share SOLVE: (4)(-7)  (-2) Then switch!

Grade your boss’ work… Answer: 14 (4)(-7)  (-2) First, (4)(-7) = - 28 Finish it! (-28)(-2) Answer: 14

= 4 (-56  7)  - 2 5  -7  -6 = 210 = - 135

Why does it all work?

Properties of Multiplication Identity a  1 = a and 1  a = a Zero Property a  0 = 0 and 0  a = 0 Property of -1 a(-1) = -a and (-1)a = -a

Distributive Property How will we use this with integer multiplication? a (b+c) = ab + bc -1 (5 + 7) = (-1)5 + (-1)7 Also, -7 = (-1) 7

Here’s How to Use It Ex.: (-7) 6 (-1) (7 6) = - 42

(-1)(-1) = ? = 1 Why??

Vocabulary Reciprocal: Two numbers whose product is 1. Ex.: reciprocal of a:

More on Reciprocal Ex.: = -2