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ALGEBRA1
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CHAPTER5.3T
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à 5.3ïGraphing Linear Equations
äïPlease complete the given ordered pairs by using the given
êêequation.
â
êêê 2x + 3y = 6ë(0, ),ï( ,0)
if x = 0,ï2(0) + 3y = 6è(0,2)ê if y = 0,ï2x + 3(0) = 6è(3,0)
êêè 3y = 6êêêêë 2x = 6
êêëy = 2êêêêêx = 3
éS
To complete the ordered pair (0, ), using the equation, 2x + 3y = 6,
substitute '0' in for 'x' and solve the remaining equation for y.
êè2x + 3y = 6ê This value of 'y' is the missing second
ê 2(0) + 3y = 6ê coordinate in the given ordered pair, (0, ).
êê 3y = 6ê The completed ordered pair is (0,2).
êêïy = 2
Similarly to complete the ordered pair, ( ,0), substitute the '0' for 'y'
and solve the remaining equation for 'x'.
êêë 2x + 3y = 6ëThe completed ordered pair is (3,0).
êêè 2x + 3(0) = 6
êêêè 2x = 6
êêêëx = 3
1ïComplete the ordered pairs (0, ), ( ,0), and (2, ), using the
êè equation 3x + 4y = 24.
êêë9
A) (0,6) (8,0) (2,─)ëB) (6,0) (0,8) (2,5)è C) (0,2) (3,0) (2,12)
êêë2
üè3x + 4y = 24êï3x + 4y = 24êë3x + 4y = 24
ê3(0) + 4y = 24ê3x + 4(0) = 24êè3(2) + 4y = 24
êê4y = 24êê3x = 24êë 6 + 4y = 24
êê y = 6êêïx = 8êêè 4y = 18
êê (0,6)êêï(8,0)êêè 18è9ë 9
êêêêêêêë y = ── = ─ï(2, ─)
êêêêêêêêè 4è2ë 2
Ç A
2ïComplete the ordered pairs, (0, ), ( ,0) and ( ,3), using the
êè equation, 5x - 3y = 15.
êêêêêêêêêè 24
A) (-5,0) (0,3) (7,3)è B) (-5,0) (0,3) (6,3)è C) (0,-5) (3,0) (──,3)
êêêêêêêêêë5
üè5x - 3y = 15êï5x - 3y = 15êë5x - 3y = 15
ê5(0) - 3y = 15ê5x - 3(0) = 15êè5x - 3(3) = 15
êë -3y = 15êê5x = 15êë5x - 9ï= 15
êê y = -5êê x = 3êêè 5x = 24
êê (0,-5)êê (3,0)êêè 24ë 24
êêêêêêêë y = ──ë(──, 3)
êêêêêêêêè 5ê5
Ç C
äïPlease find the intercepts for each equation.
âêêë -2x + 4y = 16
è if x=0, -2∙0 + 4y = 16êêif y=0,ï-2x + 4∙0 = 16
êêë4y = 16êêêê -2x = 16
êêë y = 4êêêêè x = -8
èthe y - intercept is (0,4)êïthe x - intercept is (-8,0)
éS
To find the intercepts for the equation -2x + 4y = 16, substitute '0'
in for 'x' and solve for 'y'.
êêê if x=0, -2∙0 + 4y = 16
êêêêêï4y = 16
êêêêêèy = 4
The y - intercept is the point, (0,4), on the y - axis. This is the
point where the graph crosses the y - axis.
To find the x - intercept, substitute '0' in for 'y' and solve for 'x'.
êêê if y=0,ï-2x + 4∙0 = 16
êêêêêï-2x = 16
êêêêêè x = -8
The x - intercept is the point, (-8,0), on the x - axis.ïThis is the
point where the graph crosses the x - axis.
3
êëFind the intercepts of the equation, 3x - 9y = 18.
êêêêêêêêê å
A)ï(0,-2) (6,0)ëB)ï(6,0) (-2,0)è C)ï(5,0) (0,-3)è D)ïof
êêêêêêêêê ç
üêè3x - 9y = 18êê3x - 9y = 18
êê 3∙0 - 9y = 18êë 3x - 9∙0 = 18
êêë -9y = 18êêë3x = 18
êêê y = -2êêë x = 6
êêê (0,-2)êêë (6,0)
Ç A
4
êëFind the intercepts of the equation, 2x - 3y = 7.
êêêê 7è7êêêï2êå
A)ï(3,0) (0,2)ëB)ï(0,─ ─) (─ ,0)è C)ï(4,0) (0,- ─)è D)ïof
êêêê 3è2êêêï3êç
üêè2x - 3y = 7êê 2x - 3y = 7
êê 2∙0 - 3y = 7êê2x - 3∙0 = 7
êêë -3y = 7êêë 2x = 7
êêêë7êï7êê 7ë 7
êêë y = - ─è (0,- ─)êèx = ─ë(─ , 0)
êêêë3êï3êê 2ë 2
Ç B
äïPlease graph the following lines by finding the intercepts
âêêêè2x + 3y = 6
Gâ [y= -.666x + 2] 6,6,530,151,3,14
x - interceptïif y = 0,ï2x = 6
êêêêx = 3è(3,0)
y - interceptïif x = 0,ï3y = 6
êêêêy = 2è(0,2)
éS
The equation, 2x + 3y = 6, is known to have a graph that is a straight
line.ïSince any two points determine a line, it is sufficient to find
the two points where the line crosses the two axes.ïFirst letting x = 0
and solving for y, and then letting y = 0 and solving for x.
if x = 0, thenè2x + 3y = 6êè if y = 0, then 2x + 3y = 6
êêè2∙0ï3y = 6êêêè 2x + 3∙0 = 6
êêè 0 + 3y = 6êêêë 2x + 0 = 6
êêê 3y = 6êêêêè2x = 6
êêêïy = 2êêêêè x = 3
The ordered pair (0,2) is the y - intercept and the ordered pair (3,0)
is the x - intercept.ïThese two intercepts are then plotted on the
coordinate axes and a line is drawn through them.
G 5ê Graph 3x + 4y = 12 by finding the intercepts.
A) y = .75x + 3
B) y = -.75x + 3
C) y = .25x + 4
D) y = .5x - 3
ü
If x = 0, thenêêêêêèif y = 0, then
è3∙0 + 4y = 12êêêêêë3x + 4∙0 = 12
êèy = 3êêêêêêë x = 4
êè(0,3)êêêêêêë (4,0)
Ç B
G 6ê Graph 2x - 5y = 10 by finding the intercepts.
A) y = .5x + 2
B) y = -.5x +2
C) y = .4x - 2
D) y = -.4x + 2
ü
If x = 0, thenêêêêêèif y = 0, then
è2∙0 - 5y = 10êêêêêë2x - 5∙0 = 10
êèy = -2êêêêêêëx = 5
êè(0,-2)êêêêêêë (5,0)
Ç C
G 7ê Graph y = 4x - 5ïby finding the intercepts.
A) y = -3.33x - 5
B) y = 3.33x + 5
C) y = -3.33x + 5
D) y = 3.33x - 5
ü
ïIf x = 0, thenêêêêêèif y = 0, then
ëy = 4∙0 - 5êêêêêê0 = 4x - 5
ëy = -5êêêêêêè 4x = 5
ë(0,-5)êêêêêêêï5è 5
êêêêêêêêïx = ─è(─,0)
êêêêêêêêë 4è 4
Ç D
äïPlease graph the following horizontal and vertical lines.
âêêêïGraph y = 3
Gâ [y = 0x + 3] 6,6,315,151,3,14
éS
All equations of the form, y = b, have graphs that are horizontal lines.
They have only one intercept at (0,b).ïAll equations of the form, x = a
have graphs that are vertical lines.ïThey have only the x - intercept
at (a,0).
G 8êêëGraph 2y = 8
A) y = -999x + 4
B) y = -999x - 4
C) y = 0x + 4
D) y = 0x - 4
üêThis is a horizontal line with y - intercept, (0,4)
êè 2y = 8
êëy = 4
Ç C
G 9êêèGraph 2x - 3 = 7
A) y = 0x + 5
B) y = -999x + 5
C) y = 0x - 5
D) y = -999x - 5
üêThis is a vertical line with x - intercept (5,0)
ï2x - 3 = 7
ë 2x = 7 + 3
ë 2x = 10
êx = 5
Ç B
G 10êêè Graph y = -4
A) y = -999x + 4
B) y = x - 4
C) y = -999x - 4
D) y = x + 4
üêThis is a horizontal line with y - intercept (0,-4)
Ç B
G 11êêè Graph x = -2
A) y = -999x + 2
B) y = x + 2
C) y = -999x - 2
D) y = x - 2
üêThis is a vertical line with x - intercept (-2,0)
Ç C
äïPlease graph the following lines which pass through the
origin.
âêêê Graph y = 3x
If x = 0,ïy = 3∙0êè If x = 1,ïy = 3∙1
êè y = 0êêêèy = 3
êè (0,0)êêêè(1,3)
Gâ [y = 3x + 0]6,6,530,151,3,14
éSïTo graph, y = 3x, substitute '0' for 'x' and solve for 'y'.
êêêêëy = 3x
êêêêëy = 3∙0
êêêêëy = 0
The ordered pair, (0,0), is the origin and is both the x - intercept and
the y - intercept.ïThe line passes through the origin.ïOne additional
point is needed to get a graph.ïSelect an x - value, substitute this
value into the equation and solve for y.
If x is '1', y = 3xè The additional ordered pair
êë y = 3∙1èis (1,3).ïThese two points
êë y = 3ëdetermine the graph.
GéS [y = 3x + 0]6,6,530,170,3,14
G 12êêè Graph y = 2x
A) y = 2x + 0
B) y = -2x + 0
C) y = -.5x + 0
D) y = -2x + 4
üèy = 2xêêêêêïy = 2x
êïy = 2∙0êêêêê y = 2∙2
êïy = 0êêêêêèy = 4
êï(0,0)êêêêêè(2,4)
Ç A