Hi Mik;
Find the slope and the yintercept for the line that passes through (8,2) (11,4)
The slope is the changeofy divided by the changeofx, also known as riseoverrun...
m=(yy_{1})/(xx_{1})
m=(24)/(811)
m=(2)/(19)
m=2/19
The slopeintercept formula is...
y=mx+b
b is the yintercept, the value of y when x=0.
y=(2/19)x+b
Let's plugin one set of coordinates...
2=(2/19)(8)+b
2=16/19+b
Let's add 16/19 to both sides of the equation...
(16/19)+2=(16/19)+b+(16/19)
2 16/19=b
y=(2/19)x+(2 16/19)
Let's check our results with the other set of coordinates...
y=(2/19)x+b
4=(2/19)(11)+b
4=(22/19)+b
4=(1 3/19) +b
Let's subtract 1 3/19 from both sides...
2 16/19=b
y=(2/19)x+(2 16/19)
d. Find the slope and the yintercept for the line that passes through (8,11) (4,6)
m=(yy_{1})/(xx_{1})
m=(116)/(84)
m=(17)/(12)
m=(17)/(12)
m=1 5/12
m=(1 5/12)x+b
m=(17/12)x+b
Let's plugin one set of coordinates to establish b, the yintercept.
y=mx+b
11=(17/12)(8)+b
11=(136/12)+b
11=(11 4/12)+b
11=(11 1/3)+b
Let's add 11 1/3 to both sides...
1/3=b
y=(1 5/12)x+(1/3)
Other coordinates...
y=mx+b
y=(1 5/12)x+b
6=(1 5/12)(4)+b
6=(17/12)(4)+b
6=(68/12)+b
6=(34/6)+b
6=(17/3)+b
6=(5 2/3)+b
1/3=b
y=(1 5/12)x+(1/3)
12/22/2013

Vivian L.