Algebra 1 Common Core Student Edition, Grade 8-9

> 9/3 get 9> ftcard $ 50

9/4 buy new game $19

9/7 buy new jacket $29

9/10 Aunt Sue adds $ $25

a/13 buy newheadphones $13

.red to add to be $ 2 5 _L

Yo u m ay f i n d u si n g

a number l i ne

helpful here.

MATHEMATICAL

PRACTICES

q\.V£ a ...........................

** 1 1 J Getting Ready!

You have kept tra c k o f th e a c tiv ity on a g ift

card, as shown at the right. The values are

negative (red) when you spend money and

positive (black) when you add money.

You w ant to give th e card to a frie n d. How

much money must you add to make th e card

worth $25? Explain your reasoning.

Adding and Subtracting

Real Num bers

Common Core State Standards

Prepares fo r N-RN.B.3 Explain why the sum or

product of tw o rational numbers is rational; th a t the

sum of a rational number and an irrational number is

irrational...

M P 1 , MP 3, M P 4

Objective To fin d sum s and differences o f real num bers

Lesson )

Vocabulary

• absolute value
  opposites
  addit ive inverses

Essent ial Und er st and ing Y o u c a n a d d o r s u b t r a c t a n y r e a l n u m b e r s u s in g a

n u m b e r l in e m o d e l. Y o u c a n a ls o a d d o r s u b t r a c t r e a l n u m b e r s u s in g r u le s i n v o lv in g

a b s o lu te v a lu e.

Think

How do you know

which direction to

move along the

number line?

If the number added is

positive, move to the

right. If the number

added is negative, move

to the left.

I U s in g N u m b e r Lin e M o d e ls

What is each sum? Use a number line.

0 3 + 5 Start at 3

H F- +-

2 3 4 5 6 7

move 5 units left

03 + (-5)

0-3 + 5

0 -3 + (-5)

H

H h H 1 -

-4 -3 -2 -1 1

m o v e 5 units r ig h t ^

+- H 1 - H h

-4 - 3 -2-1 0 1

HHm o v e 5 u n its le f t

-*-♦------ 1 ------ 1 ------ 1 ------h

-8 -7 -6 -5 -4

H h

3 + 5 = 8

Move 5 units right.

3 + ( - 5 ) = - 2

-3 + 5 = 2

-3 + (-5) = -8

Got It? 1. W h a t i s -8 + 4? Use a nu m b e r line.

30 Ch ap t er 1 Fo u n d a t i o n s f o r A l g e b r a