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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