Question

Determine whether the following set of points lies on a straight line

(1,2,-1), (2,4,-3), (4,8,-7)

Answer 1

Direction cosines? or maybe you can use the unit vector.

Answer 2

Not sure.. Direction vector or displacement vector? How do you do this in steps?

Answer 3

I'm not sure if it is correct
For AB, it is i +2j -2k if you can't see it clearly

Answer 4

I thought that's how to do it. Thank you very much, it's correct.

Answer 5

You're welcome

Answer 6

Find the slope between each set:
AB, BC, and AC.

If they are all equal, they are collinear.

Slope = (y1 - y2) / (x1 - x2)

AB = (4 - 1) / (3 - 1) = 3 / 2
BC = (10 - 4) / (7 - 3) = 6 / 4 = 3 / 2
AC = (10 - 1) / (7 - 1) = 9 / 6 = 3 / 2