pick any value of s and t you feel like, I will do one
let s = 2, t = 1
(x,y,z) = (3,4,-1) + (2,2,-8) + (2,-5,3) = (7, 1, -6)
why are the answers in the back of my textbook,[3,4,-1], [4,5,-5], [2,3,3]
It said, find three points, that is
any three point from the infinite number of points that would be possible
to get my point, as I said, I let s=2 and t=1
to get their point of (3,4,-1), they used s=0 and t=0
to get their point of (4,5,-5) they used s=1 and t=0
You can use any value of s and t that you want, it was rather silly to even give any answer at all in the back of the book.
It only confuses the student if he/she does not get that particular answer.