Properties of Real Numbers Properties of Addition Multiplication

Properties of Real Numbers

Properties of Addition & Multiplication: For all real #’s, a, b, c… l Closure: then a+b is a real number ab is a real number l l Commutative: a + b = b + a ab = ba Associative: (a+b)+c = a+(b+c) (ab)c = a(bc) Identity: a + 0 = 0 + a = a a*1 = 1*a = a Inverse: a + (-a) = 0

Distributive Property For all real numbers a, b, and c: a(b + c) = ab + ac and (b + c)a = ba + bc)

State a property to justify the following statements… l 6 +(-3) = (-3) + 6 l 3(4 a+5) = 12 a + 15 l (x+3) + 6 = 6 + (x+ 3) l -5 + 5 = 0

State a property to justify the following statements… l 2(4 – 5) = (4 - 5)2 l -5 + (x + 2) = (-5 + x) + 2 l 4 ( 1) = 4

Using Properties for Mental Math l A movie ticket costs $7. 75. A drink costs $2. 40 and popcorn is $1. 25. What is the total cost?

Using Properties for Mental Math l You buy a sandwich for $2. 95, an apple for $. 45, and a bottle of juice for $1. 05. What is the total cost?

Simplify – using properties

Homework l Worksheet