Properties and Numbers 1.4
Deductive Reasoning Using facts, properties or rules to reach a valid conclusion Conjecture: statement that could be true of false Counter Example: an example that shows a statement is not true.
Ex: State whether each conjecture is true. If not give a counterexample. The sum of an even and an odd number is always even. False: 4+1 =5 which is odd
Commutative Properties: Change Order Addition Rule: Ex: Multiplication Rule: Ex:
Associative Properties: Change Grouping Addition (a+b)+c =a+(b+c) Ex: Multiplication Ex:
Identity Properties Addition (0) Rule: a + 0 = a Ex: = 7 Multiplication(1) Rule: Ex:
Name the Property Example: 4+(a+3)=(a+3) +4 Answer: Commutative because the numbers changed order Example: 1(3c)=3c Answer: Identity Property because you multiplied by 1 and the number did not change
Name the Property Ex: 14+(9+10)=(14+9)+10 Answer: Associative because the grouping symbols changed Ex: d+0 =d Answer: Identity of addition because you added by 0 and the result stayed the same
Simplify the phrase using the properties Ex: 9 +(5+y)
Answer the following 2 questions: 1.) Is division of whole numbers associative? If not give a counterexample 2.) Is subtraction of whole numbers commutative? If not give a counterexample
Homework Page 22 (14-39 all, even)