\begin{tikzpicture}
    \begin{axis}[view={40}{30},
                 zlabel=$z$,
                 xlabel=$x$,
                 ylabel=$y$,]
        \addplot3[color=red,
                  mesh,
                  samples=60]
                 {x^2 - y^2};
    \end{axis}
\end{tikzpicture}
        

\begin{tikzpicture}
    \begin{axis}[xmin=-3, xmax=3,
                 ymin=-3, ymax=3,
                 zmin=0, zmax=2,
                 view={320}{20},
                 zlabel=$z$, xlabel=$x$, ylabel=$y$,
                 unit vector ratio = 1.5 1.5 1]
        \addplot3[mesh,
                  surf,
                  shader=faceted,
                  samples=60,
                  domain=-3:3]
                 {(x^2+2*y^2)*exp(-x^2-y^2+1)};
    \end{axis}
\end{tikzpicture}