# 2-2 Properties from Algebra

## Presentation on theme: "2-2 Properties from Algebra"— Presentation transcript:

2-2 Properties from Algebra
Notes on worksheet

Properties from Algebra
See Worksheet! Addition Property Subtraction Property Multiplication Property Division Property You can +/-/x/÷ the same number on both sides of an equation

Properties from Algebra
Substitution: think “replace” Ex: a+b=c, if c = 8 then a + b = 8 Questions on Substitution??? We use this ALOT in Proofs! Reflexive: a # equals itself (same on both side) Symmetric: switch the side of the equal sign it is on Transitive (3 parts) Ex: = • 2 = 10 6 + 4 = 5 • 2

Properties from Algebra
Properties of Congruence: Properties of Equality where the equal sign is replaced with a congruency sign. Distributive Property If a(b + c), then ab + ac What do you notice about all the properties? They are If-Then statements!

Example Justify the statement: If WX = YZ, then WY = XZ
addition: we added the segment XY to both sides of the original equation W X Y Z

Example Justify the statement: If WY = XZ, then WX = YZ
subtraction: we subtracted the segment XY from both sides of the original equation W X Y Z

TOO—on Whiteboards!!!! If 4x = -24, then x = -6 DIVISION!
If a = b and b = c then a = c. Transitive! Angle A = Angle A Reflexive!

Homework Worksheet 2-1 and 2-2
Skip #14 the Proof, We will do it together tomorrow