Question

Show that the following points are collinear:

A(–5, 1), B(5, 5) and C(10, 7)

Answer 1

`"Let " A(x_1=-5,y_1=1), B(x_2=5,y_2=5) and C(x_3= 10,y_3=7)`be the given points. 

` Now, x_1(y_2-y_3)+x_2(y_3-y_1)+x_3(y_1-y_2)`

`=(-5)(5-7)+5(7-1)+10(1-5)`

`=-5(-2)+5(6)+10(-4)`

`=10+30-40`

= 0

Hence, the given points are collinear.