## Calculus (3rd Edition)

$$4x+3y+z=8, \quad 4x+3y+2z=8$$ (Other answers are possible.)
The planes $$4x+3y+z=8, \quad 4x+3y+2z=8$$ have the trace $$4x+3y=8$$ in the $xy$-plane. This is because, if we set $z=0$ in the equations, we will obtain the trace equation. Note that many other answers are possible.