Hi again, was wondering how to solve this question:

let v vector be from A(2, 0, -1) to B(1, 2, -3) find 2 vectors parallel to v vector.

I found that v=B-A=(-1,2,-2) but don't know how to find "2" vectors parallel to this.

You can just add any constant in front of the vector and multiply. The types of parallel line created hen you premultiply by a positive constant is called a like parallel vector, and a negative constant will give you an unlike parallel vector.

You can try this with a 2D vector, say, (1,1) multiplying by 2 will give (2, 2) and if you draw them on the same scale, they'll be parallel, but only not of the same length.