Properties of Real Numbers Commutative Property of Addition a + b = b + a Ex) (- 7) + ( 3) = ( 3) + ( -7) = - 4 Ex) = Commutative Property of Multiplication ab = ba Ex) ( 4)(-3) = ( -3)(4) = - 12 Order doesn’t matter.

Associative Property of Addition (a + b) + c = a + ( b + c) Ex) ( 3 + 6) + ( - 4) = 3 + ( 6 + (-4)) 9 + ( -4 ) = 3 + ( 2) 5 = 5 True Because of this property, we can leave off the parentheses when doing Addition.

Associative Property of Multiplication Ex)(ab)c= a(bc)

Is this an example of Commutative or Associative Properties? Ex)Commutative I didn’t Regroup, I only rearranged the order inside the Parenthese. Ex) ( 4 + 9) + 7 = 4 + ( 7 + 9) Associative and Commutative I regrouped the numbers and I rearranged the order of the 9 and 7.

Identity Properties Additiona + 0 = a and 0 + a = a Ex) = 4 Multiplication a( 1) = a and ( 1)a = a Ex) We use this property to find Equivalent Fractions.

Inverse Properties Additive Inverse a + ( - a) = 0 Ex) 5 + ( -5) = 0 Multiplicative Inverse Ex)

Distributive Property a ( b + c ) = ab + ac a ( b – c ) = ab – ac Ex) Verify 3( 9 – 4 ) = 3(9) – 3 (4) 3 ( 5) = 27 – = 15

More Examples 6( x + 4) = 6x + 6(4) = 6x ( 4x – 8) = - 4x ( 3x + 2) + 7 = 8( 3x) + 8(2) + 7 = 24x = 24x (x) – 5(y) = 5 ( x – y )

Use a Property to Simplify the Expressions Ex) 9 + ( 13) + ( -9) + 7 Ex) ( 47) ( - 7) Ex) x + (-x ) + (2/3)(3/2) Ex) 9.8x + 7 – 7 – 9.8x

More Examples Rewrite each expression using the Distributive Property. 8( x – 5) = 9x + 9y + 9z = - ( 7x - 2y + 3z ) =