Math 7 ( Period 4)

 The Commutative & Associative Properties 1.7

What are properties... They are characteristic of math operations that can be identified

Why are they your friends?  (BFF) you can count on properties they always work they will NOT let you down... there are NO COUNTER EXAMPLES..

 Properties are the exceptions to Aunt Sally

These properties give you a choice when
it is ALL MULTIPLICATION or
it is ALL ADDITION

(they DO not work for subtraction or division)  lots of counterexamples for those...

 10 – 2 does not equal 2- 10

Commutative property (works for all Multiplication or All addition)

You can switch the order and still get the same sum or product

This is the property that you can hear because you switched the order

 a+ b = b + a  or ab= ba 

Commutative Big C looks like an ear... 

Why care?  it makes the math easier ... sometimes

 Which  would you rather multiply

(2)(543) (5)  or (2)(5)(543)

Associative Property    another friend

 This friend allows you to group all multiplication or all addition ANYWAY you choose

a + (b+ c)  = ( a + b)  + c

a(bc) = (ab)c

again.. to make the math easier

This is the property that you can SEE instead of hear because  you use (parentheses) but you don’t change the ORDER GIVEN

[(543)(5)](2)  what would Aunt Sally say you MUST do? 

but our friend the associative property allows use to move the brackets...

(543)[(5)(2)] which is so much easier to multiply—even in your head...