SOLUTION: http://www.usatestprep.com/modules/gallery/files/5/519/519.png Determine the equation of the line passing through points C and D.

Algebra ->  Linear-equations -> SOLUTION: http://www.usatestprep.com/modules/gallery/files/5/519/519.png Determine the equation of the line passing through points C and D.      Log On


   

Question 939515: http://www.usatestprep.com/modules/gallery/files/5/519/519.png
Determine the equation of the line passing through points C and D.
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!
linear equation is: y=mx%2Bb where m is a slope and b is a y-intercept; so, we need m and b
Determine the equation of
from the graph we see that the line passing through points C =(2,-2) and D=(4,0) which means:
if x=2 => y=-2
and
if x=4 => y=0=> a x-intercept highlight%28x=4%29
then we will use these points to set the system of two equations to find m and b
y=mx%2Bb ........if x=2,y=-2 we have
-2=m%2A2%2Bb ........eq.1

y=mx%2Bb ........if (4,0) we have
0=m%2A4%2Bb ........eq.2
solve the system:
-2=2m%2Bb ........eq.1
0=4m%2Bb ........eq.2
----------------------------------------------subtract eq.1 from eq.2
0-%28-2%29=4m%2Bb-2m-b
2=2m
m=2%2F2
highlight%28m=1%29
now find b
0=4m%2Bb ........eq.2
0=4%2A1%2Bb
0=4%2Bb
-4=b
highlight%28b=-4%29
so, your equation is: y=x-4