Ch. 2-3 to 2-6 Adding, Subtracting, Multiplying, and Dividing Integers NO CALCULATORS-----for today !!!!!!! C. N. Colon St. Barnabas HS Algebra 1

Integers Integers are the whole numbers and their opposites (no decimal values!) We will use integers in our study of operations with signed numbers to review the rules (the homework assignment will contain decimals and fractions, as well as integers) Example: -3 is an integer Example: 4 is an integer Example: 7.3 is not an integer

Adding integers comes down to two rules How do we add integers Adding integers comes down to two rules Rule 1: If the signs are the same, simply add the numbers and keep that value with the same sign Example: -4 + -8 = -12 (because 4 + 8 is 12) Rule 2: If the signs are different, simply use the sign of the number with the greater absolute value, then just subtract or find their difference Example: 3 + -7 = -4 (because 7 – 3 is 4)

How do we subtract integers Subtraction and addition are friends (really are inverse operations that complement each other) REMEMBER We never really subtract …….we add the additive inverse! subtraction just changes itself to addition by changing the second number’s sign. Make sure you follow the addition rules after that. Example: -4 – 6 means -4 + -6 = -10

Multiplication and Division They, too, are friends so they share the rules Rule 1: When the signs are the same [(+ ,+) or (-, -)] simply do the operation and the answer will be positive Example: -25 ÷ -5 = 5 (since it is (-, -) same signs) Rule 2: When the signs are different [(+, - )or (- ,+)] simply do the operation and the answer will be negative Example: -4 • 8 = -32 (since it is (- ,+)

You try some a)-5 + 8 b)-3 + 2 c)-11 + -4 3 -1 -15 d)-11 – 4 e)15 – (-2) f) -1 – (-6) -15 17 5 g)7 • -4 h)-8 • -3 i) -11 • 2 -28 24 -22 j) -36 ÷ 9 k)12 ÷ -4 l) -28 ÷ -7 -4 -3 4

ASSIGNMENT p. 62 # 4-32 (mo4) p.67 # 4-34 (mo4) p. 70 # 4-28 (mo4)