I need to express the following equation in the form of matrices A x = b

This is an easy concept except for the fact that this system has more unknowns than equations. Should I solve for w in terms of x, y z to eliminate one variable????

4x - 2y +z - 3w = -3

x + y -4z + 2w = 6

2x + 3y - 5z - w = 4

If this were a square system there is nothing to figure out but sinc it is not...???? Thanks, Frostking