Algebra 1 Common Core Student Edition, Grade 8-9

G o t It? 1. W hat are the x- a n d y-intercepts of th e graph of each equation?

a. 5x - 6y = 60 b. 3x + 8y = 12

Think
What points do the
intercepts represent?
The x-intercept is —2,
so the graph crosses the
x-axis at ( - 2 , 0). The
y-intercept is 1, so the
graph crosses the y-axis
at (0,1).

Thi nk

Why w rite x = 3 in

standard form?

When you w rite x = 3

in standard form , you can

see tha t, fo r any value

of y, x = 3. This form

of the equation makes

graphing the line easier.

Graphing a Line Using Intercepts

What is the graph of x — 2y = — 2?

An equation o f the line The coordinates o f at Find and p lo t the x- and y-intercepts.

least tw o points on Draw a line through the points,

the line

Step 1 Find the intercepts.

x — 2y = - 2

x — 2(0) = - 2

x = —2

x - 2y = - 2

0 - 2y = - 2

~2y= ~2

y=1

Step 2 Plot ( - 2 , 0) and (0,1).

Draw a line

the points.

uyn

y

*■)

n

z

X

0

i

G o t It? 2. W hat is th e g raph of 2x + 5y = 20?

If A = 0 in th e stan d ard form A x + By = C, th e n you can w rite th e eq u a tio n in the

form y = b, w here b is a constant. If B = 0, you can w rite th e eq u a tio n in th e form

x = a, w here a is a constant. The graph of y = b is a horizontal line, a n d th e graph of

x = a is a vertical line.

Graphing Horizontal and Vertical Lines

What is the graph of each equation?

Qx = 3 0J=3

l x + Oy = 3 Write in standard form. Ox + ly = 3

y i

L-)

X

0

(^1) yt
J
For all values
ofy, x = 3.
< 9 G o t It? 3. W hat is th e graph of each equation?
a. x = 4 b. x = -1 c. y = 0 d. y = 1
PowerAlgebra.com Lesson 5-5 St an d ar d Fo r m

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