Question

find the value of p for which the points are (-1,3),(2,p),and (5,-1) are collinear

Answer 1

0 i think it is 0 but confirm it

Answer 2

see if they are collinear means that they are in same line
i will tell you the steps
first find the slope m= y1-y2/x1-x2  with points (-1,3) and(5,-1)
then find the second slope of(-1,3) and(2,p)
then as they are same line 
m1=m2
now equalize both the slope
you get ur p
i did not wanted to write the solution as i wanted u to do this sum