Multiplication and Division of Integers

Multiplying Positives and Negatives Hey- your idea was great! Any idea about multiplying or dividing with negative numbers, please share their thought!

The good news!! We get to multiply or divide like normal! We just need to worry about when it’s a positive or negative solution.

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 =

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