Question 987079
Are these three points collinear?

{{{(8-4)/(4-12)=(4-1.5)/(12-17)}}}
{{{4/(-8)=2.5/(-5)}}}
{{{-1/2=-1/2}}}
Yes, common slope using these points.


Pick any of the three points and use now known slope, and fill-in the point-slope form equation.  Do whatever you want with it.


{{{y-4=-(1/2)(x-12)}}}