Algebra 1 Common Core Student Edition, Grade 8-9

© G o t It? 5. a. In P roblem 5, su ppose the store charged $15 for each movie. W hat

eq u a tio n describes th e n u m b ers of songs an d m ovies you can p urchase

for $60?

b. Reasoning W hat d o m ain a n d range are reasonable for th e equ atio n in

p art (a)? Explain.

Co n cep t Su m m a r y Li near Equat i ons

You can describe any line using one or m ore of these form s of a linear equation. Any two

eq u atio n s for th e sam e line are equivalent.

Graph Forms

Slope-lntercept Form

7 y y-intercept(0,6) y = mx + b

Slope Y

m = - i

1 Pn i r

(3, 4)

x-intercept

(^1) L (9, 0)
L
X
— 0 i
y = — gX + 6
Point-Slope Form
y - y l = m { x - Xj)
y — 4 = —| (x —3)
Standard Form
A x + B y = C
2x + 3y = 18
Lesso n Ch eck
Do y o u k n o w H OW?

1. W hat are the x- and y-intercepts of th e graph of
   3x — 4y = 9?


2. W hat is th e graph of 5x + Ay = 20?


3. Is the graph of y = - 0 .5 a horizontal line, a vertical
   line, or neither?


4. W hat is y = \x + 3 w ritten in stan d ard form
   using integers?


5. A store sells gift cards in p reset am ounts. You can
   purchase gift cards for $10 or $25. You have sp en t
   $285 on gift cards. W rite a n equ atio n in stan d ard
   form to rep resen t this situation. W hat are th ree
   com binations of gift cards you could have purchased?

MATHEMATICAL

Do y o u UN DERSTAN D? Vg j J PRACTICES

6. V o c a b u l a r y Tell w h e th e r each linear equation

is in slope-intercept form , point-slope form , or

standard form.

a. y + 5 = —(x - 2)

b. y = - 2 x + 5

c. y - 10 = —2(x — 1)

d. 2x + 4 y = 12

7. Reasoning Which form
   w ould you use to w rite an
   equation of the line at the
   right: slope-intercept form ,
   point-slope form, or standard
   form? E x p l a i n.

f

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