Download 1.5 Adding and Subtracting Real Numbers Template

Algebra IA
Ch.1: Foundations for Algebra
1.5 Adding and Subtracting Real Numbers
Sum – the answer when you add
Template
 Ex.1: What is each sum? Use a number line, if necessary.
a. 8 + 4
b. 8 + (-4)
c. -8 + 4
d. -8 + (-4)
 Absolute Value – the distance a number is from zero on a number line.
Therefore, absolute value can never be negative.
Symbol - │x│
Examples:
Situation
Positive + Positive
7+2
Negative + Negative
-7 + -2
Positive + Negative
7 + -2
Negative + Positive
-7 + 2
Rules for addition
Rule
Just add
Take the absolute value of each.
Add.
Attach the negative sign.
Take the absolute value of each.
Subtract the smaller from the larger.
Attach the original sign of the larger absolute
value.
Take the absolute value of each.
Subtract the smaller from the larger.
Attach the original sign of the larger absolute
value.
Greatest
Absolute
Value
Rules!
 Ex.2: What is each sum? Use absolute value, if necessary.
a. -16 + (-8)
b. -11 + 9
c. 9.2 + (-11.3)
d.
2  1
  
3  4
 Opposites – 2 values whose sum is zero. Also called Additive Inverses
-a is read “the opposite of a” -(-2) = 2
-(5) = -5 -(0) = 0
 Inverse Property of Addition – a + a = 0
Difference – answer when you subtract
Rule for subtraction – subtraction is the same as adding the opposite
Ex.3: What is each difference?
a. -8 – (-13)
b. 9 – 9
c. 12 – 14
d. -11 – 15
Ex.4: For what values of a and b does
a b  b  a .
Ex.5: A robot submarine dives 803 feet to the ocean floor. It rises 215 feet as the
water gets shallower. Then the submarine dives 2619 feet into a deep crevice.
Next, it rises 734 feet to photograph a crack in the wall of the crevice. What is the
location of the crack in relation to sea level?
HW: pg.41 11-40, 55-65 (no calculator)