Let F$($x$,$ y$,$ z$)=$ x $2$yz $1.($a$)$ Find an equation for the tangent plane to the surface F$($x$,$ y$,$ z$)=0$ at the point $(3,1/3,1).($b$)$ Find parametric equations for the normal line to the surface F$($x$,$ y$,$ z$)=0$ at the point $(3,1/3,1).$