I will do the first third (the x part)

1: gather all of the x,y and z stuff together this gives

First we factor a 3 (the lead coefficient of the x squared term) out of only the x terms this gives

Now we take half of the coefficient of the x term and square it.

Now we add this inside the parentheses on the left to get

but we also have to add this to the other side so we don't change the equation. Also don't forget to multiply it by the 3 out side the parenthesis to get

Now factor the x's to get

Now you just need to do the z's the y is already a perfect square.