What is the vector from A to B? What is the vector from A to C? Do you know what "colinear" means?
The position vectors of points A, B and C are 9i-10j , 4i+2j and Ki-2j respectively.
Find the value of k if the points A,B and c are collinear.
If are collinear, then: .
We have: .
. . . . . . . . .
From : .
Subtitute into : .