Question

Find the value of y for which the points (5,-4),(3,-1)and(1,y)are collenior?

Answer 1

since the points are given to be collinear,, then the area of the triangle formed by these points, will be zero ... hence
1/2[5(-1-y)+3(y+4)+1(-4+1)]=0
-5-5y+3y+12-3=0
2y=4
y=2