Find the vector in ℝ^3 from point A=(x,y,z) to B=(−8,2,5).

Answer 1

You are working from an initial point and a direction that your vector will be going.
The direction is (x,y,z) - (-8,2, 5)
= (x+8,y-2,z-5)
and if you sub in a point then
the vector is (-8,2,5) + t(x+8,y-2,z-5)