Name
Date
Class
Practice A
LESSON
5-6
Slope-Intercept Form
Write the equation that describes each line in slope-intercept form.
2; y-intercept  2
1. slope  __
3
y
3. slope  2,  3, 5  is on the line.
Find the y-intercept: y  mx  b
x
2. slope  1; y-intercept  8
y
x
5   2 

5
b

b

b
Write the equation: y 
x
Write each equation in slope-intercept form. Then graph the line.
1x
4. y  2x  4
5. y  3  __
6. 2x  3y  6
2
��
��
�
�
�
�
�
�
�
�
�
�
�
�
�
��
��
�
�
�
�
��
�
��
��
��
��
��
��
��
7. A school orders 25 desks for each classroom,
plus 30 spare desks. The total number ordered
as a function of the number of classrooms is shown
in the graph.
�
�
�
���������
���
a. Write the equation represented by the graph.
���
���
b. Identify the slope and y-intercept and describe their
meanings.
�������������
���
���
���
���
���
���
c. Find the total number of desks ordered if there are
24 classrooms.
��
�
�
�
�
��
��
��
��
��
��
����������
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
a107c05-6_pr.indd 43
43
Holt Algebra 1
12/12/05 7:50:27 PM
*À>V̈ViÊ
3LOPE)NTERCEPT&ORM
--"
x‡È
*À>V̈ViÊ
3LOPE)NTERCEPT&ORM
--"
x‡È
7RITETHEEQUATIONTHATDESCRIBESEACHLINEINSLOPEINTERCEPTFORM
7RITETHEEQUATIONTHATDESCRIBESEACHLINEINSLOPEINTERCEPTFORM
SLOPE??
YINTERCEPT
SLOPEYINTERCEPT
Y
Î
X
Ó
SLOPEYINTERCEPT
Y £ X
n
SDS
Î DB
££ B
È
YINTERCEPT
SLOPE??
££
YÊÊÊÓXÊÊ{
Y
Y
Y
X
X
YÊÊXÊÊÎ
!SCHOOLORDERSDESKSFOREACHCLASSROOM
PLUSSPAREDESKS4HETOTALNUMBERORDERED
ASAFUNCTIONOFTHENUMBEROFCLASSROOMSISSHOWN
INTHEGRAPH
.EW$ESKS
YÊÊÓxXÊÊÎä
B )DENTIFYTHESLOPEANDYINTERCEPTANDDESCRIBETHEIR
Ϝ«i\ÊÓxÆʘՓLiÀʜvÊ`iÎÃÊ«iÀ
V>ÃÃÀœœ“ÆÊY‡ˆ˜Ì\ÊÎäÆʘՓLiÀʜvÊë>ÀiÊ`iÎÃ
MEANINGS
x‡È
œÌʏ}iLÀ>Ê£
*À>V̈ViÊ
3LOPE)NTERCEPT&ORM
x‡È
X
X
YÊÊÎXÊÊÓÓ
Ϝ«i\ÊÎÆʘՓLiÀʜvʅœÕÀÃÊ«iÀ
ÜiiŽÆÊY‡ˆ˜Ì\ÊÓÓÆʅœÕÀÃÊ>Ài>`ÞÊܜÀŽi`
X
6OLUNTEER(OURS
4IMEWEEKS
ÇäʅœÕÀÃ
œÌʏ}iLÀ>Ê£
,iÌi>V…
3LOPE)NTERCEPT&ORM
MISTHESLOPE
BISTHEYINTERCEPT
!LINEHASASLOPEOFnANDAYINTERCEPTOF7RITETHEEQUATIONIN
SLOPEINTERCEPTFORM
YMXB
3UBSTITUTETHEGIVENVALUESFORMANDB
YX
{ÊXÊÊ{
YÊÊÊÚÚ
Ç
4HELINETHATPASSESTHROUGHSDAND
SDS(INT&INDTHESLOPEFIRSTD
YMXB
SLOPE??
SDISONTHELINE
Y
!NEQUATIONISINSLOPEINTERCEPTFORMIFITISWRITTENAS
YÊÊÎXÊÊxÊ
YÊÊn
#OPYRIGHT©BY(OLT2INEHARTAND7INSTON
!LLRIGHTSRESERVED
--"
SLOPEYINTERCEPT
7RITETHEEQUATIONTHATDESCRIBESEACHLINEINSLOPEINTERCEPTFORM
SLOPESDISONTHELINE
SLOPE??
YINTERCEPT
ÎÊXÊ£
YÊÊÊÚÚ
Ó
xÊXÊx
YÊÊÊÊÚÚ
Ó
C &INDTHENUMBEROFHOURSWORKEDAFTERWEEKS
#OPYRIGHT©BY(OLT2INEHARTAND7INSTON
!LLRIGHTSRESERVED
--"
#LASSROOMS
ÈÎä
MEANINGS
??
XÊ£
7RITETHEEQUATIONY
B )DENTIFYTHESLOPEANDYINTERCEPTANDDESCRIBETHEIR
B
Y
WORKASAFUNCTIONOFTIME
Î {
£ B
A 7RITEANEQUATIONTHATREPRESENTSTHEHOURS$ANIELWILL
C &INDTHETOTALNUMBEROFDESKSORDEREDIFTHEREARE
CLASSROOMS
$ESKS/RDERED
$ANIELWORKSASAVOLUNTEERINAHOMELESSSHELTER
3OFARHEHASWORKEDHOURSANDHEPLANSTO
CONTINUEWORKINGHOURSPERWEEK(ISHOURSWORKED
ASAFUNCTIONOFTIMEISSHOWNINTHEGRAPH
A 7RITETHEEQUATIONREPRESENTEDBYTHEGRAPH
X
Ó
ÚÚ
S ÊxÊ D ÊT£äÊEÊB
Î
{ÊXÊ{
YÊÊÊÚÚ
Î
Y
7RITEEACHEQUATIONINSLOPEINTERCEPTFORM4HENGRAPHTHELINE
DESCRIBEDBYTHEEQUATION
Y??
X
XY
YX
YÚÚ
ÊX
YÊÊÊÚÚ
Ê£ÊXÊÊÎ
Ó
7RITEEACHEQUATIONINSLOPEINTERCEPTFORM4HENGRAPHTHELINE
Y??
X
XY
YX
£ÊXÊÊÈ
YÊÊÊÊÚÚ
Î
Y
7RITETHEEQUATIONY Ó X
YÊÊÓX
Y
È
&INDTHEYINTERCEPTYMXB
SLOPEYINTERCEPT
È B
SLOPE??
SDISONTHELINE
YÊÊ{XÊÊÎ
Y
(OURS7ORKED
ÚÚ
ÊÓÊ
SLOPESDISONTHELINE
&INDTHEYINTERCEPTYMXB
!LINEHASASLOPEOF4HEORDEREDPAIRTEISONTHELINE7RITETHE
EQUATIONINSLOPEINTERCEPTFORM
YÊÊÎXÊÊn
3TEP&INDTHEYINTERCEPT
YMXB
7RITEEACHEQUATIONINSLOPEINTERCEPTFORM4HENGRAPHTHELINE
DESCRIBEDBYTHEEQUATION
YX
XY
YÊÊÎXÊÓ
YX
YÊÊXÊÓ
Y
ÎÊXÊÊÓ
YÊÊÊÊÚÚ
Y
3UBSTITUTETHEGIVENVALUEFORM
3UBSTITUTETHEGIVENVALUESFORXANDY
B 3OLVEFORB
B
Y
?
?
Ó
YXB
SDB
3TEP7RITETHEEQUATION
YMXB
X
X
B )DENTIFYTHESLOPEANDYINTERCEPTANDDESCRIBETHEIR
MEANINGS
Ϝ«i\Ê{ÆÊVœÃÌÊ«iÀÊõÕ>ÀiÊvœœÌÆ
ÊY‡ˆ˜Ì\ÊÎääÆÊVœÃÌʜvʈ˜ÃÌ>>̈œ˜
C &INDTHETOTALCOSTIFTHEAREAISSQUAREFEET
#OPYRIGHT©BY(OLT2INEHARTAND7INSTON
!LLRIGHTSRESERVED
YX
X
3UBSTITUTETHEGIVENVALUEFORMANDTHEVALUEYOUFOUNDFORB
7RITETHEEQUATIONTHATDESCRIBESEACHLINEINSLOPEINTERCEPTFORM
YINTERCEPT
SLOPE??
.EW#ARPET
£ÊXÊÊÎ
YÊÊÊÊÚÚ
{
SLOPEYINTERCEPT
YÊÊxX
SLOPEYINTERCEPT
YÊÊÇX
YÊÊÎX
£ÊXÊʙ
YÊÊÊÊÚÚ
Ó
SLOPEISSDISONTHELINE
SLOPEIS??
SDISONTHELINE
YÊÊXÊÊÎ
SLOPEISSDISONTHELINE
!REASQFT
f£nää
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
AK4up.indd 85
4OTAL#OST
A 7RITEANEQUATIONTHATREPRESENTSTHETOTALPRICEAS
YÊÊ{XÊÊÎää
AFUNCTIONOFAREA
4HE*OHNSONSAREPUTTINGNEWCARPETINTHEIRHOME
)NSTALLATIONISANDTHECARPETINGCOSTSPER
SQUAREFOOT4HETOTALPRICEOFTHEJOBASAFUNCTIONOF
AREAISSHOWNINTHEGRAPH
œÌʏ}iLÀ>Ê£
#OPYRIGHT©BY(OLT2INEHARTAND7INSTON
!LLRIGHTSRESERVED
85
œÌʏ}iLÀ>Ê£
Holt Algebra 1
12/12/05 7:50:22 PM