Adding Real NumbersOne for you , two for me…..

What does closure mean?

Add 2+ 3. What answer do you get?Add 12 + 24. What answer do you get?When you add any two real numbers, how many answers do you get?

This is the meaning of the closure property of addition.

How do I add using a number line?

Add 6 + (-5)First mark 6 on the number lineThen move 5 spaces in the OPPOSITE direction!What is your answer?

Now you try

-2 + 5

3 + (-6)

But what if I don’t want to use a number line?

1. Isolate your quantities2. Combine your positive terms3. Combine your negative terms4. Think MONEY!!!!!!!!!!! (Positive numbers are

what you have in your pocket, negative numbers are what you owe)

3 + 4 + (-5) + (-3) + 12 + (-2)

How does the associative property help?

2 + ( -2 + 5)

Think associations

(2 + -2) +5

2 and –2 are additive inverses so their sum is 0

What is left? 5!!!!!!!

Give examples of properties

Commutative Property: a+b = b+a. Inverse Property of Addition: a + -a = 0Identity Property of Addition: a+ 0 = a

Now you do these with numbers!

Real Life ApplicationA company has a profit if the income (receipts) is more than the expenses (costs). But if the expenses are more, the company has a loss.

Profits are denoted with positive numbers and losses are shown using negative numbers

So let’s tryIn January, my business lost $13143 and in February, I lost another $6783. In March, I lost $4735. But business picked up in April through June with profits of $3825, $7613, and $12933Please help me find out if I have an overall profit or loss!

Now it is YOUR TURN!Section 2.3 in the practice workbook

DON’T FORGET!!!!

Quiz 9/8 covers sections 2.1- 2.3

Vocabulary Due September 15

Tutoring Tuesday through Friday mornings at 8:15 AM