Question

Find the value of k, for which the points (7,2),(5,1)and (3,k) are collinear.

Answer 1

if these points are collinear then the area of triangle =0
so
1/2(7(1-k)+5(k-2)+3(2-1))=0
1/2(7-7k+5k-10+3)=0
1/2(-2k)=0
k=0