Apply the Karnaugh map method to find all simple Boolean expressions for the Boolean function (w ∨ x ∨ y ∨ z)(w' ∨ x' ∨ y' ∨ z').

I started off like this... with the truth table

w x y z and everything and then.. when I reach to the table where it goes something like this.. wx,wx',w'x'and w'x and yz,yz',y'z' y'z

It sort of stuffs up from there... :\

can some one shed some light on this thanks