Originally Posted by

**romsek** I don't think you got any of #2 correct.

For example the 4th one.

$\vec{u}$ takes us to (A+B, 0, 0)

$\vec{u}-\vec{v}$ takes us to (A+B, A-D, 0)

$\vec{u}-\vec{v}-\vec{z}$ takes us to (A+B, A-D, A-E)

This is off of the cube so it's useful to use a different starting point on the cube.

Since these vectors aren't tied to any particular point in space we can use H as the starting point as well.

Doing this we find that (H+B, H-D, H-E) = B

and so the vector that represents $\vec{u}-\vec{v}-\vec{z}$ is $\vec{HB}$

see if you can rework the first 3. Picking the correct starting point is the key to this.