Question

If the points (1, 4) (r, -2), (-3, 16) are collinear. find r

Answer 1

if three points (a,b), (c,d), (e,f) are collinear then (d-b)/(c-a)=(f-b)/(e-a)....
now here since the three points are colinear
then ((-2)-4)/(r-1)=(16-4)/(-3-1)
or (-6)/(r-1)=12/(-4)
or 6 /(r-1)=3
or r-1=2
or r=3