Plot3D[x^2-2y^2,{x,-3,3},{y,-4,4},AxesLabel->{"x","y","z"}]

ContourPlot[x^2-2y^2,{x,-3,3},{y,-4,4}]

Plot3D[Log[x^2-2y^2],{x,-3,3},{y,-4,4},AxesLabel->{"x","y","z"}]

ContourPlot[Log[x^2-2y^2],{x,-3,3},{y,-4,4}]

Plot3D[1/(x^2-2y^2),{x,-2,2},{y,-3,3},AxesLabel->{"x","y","z"}]

ContourPlot[1/(x^2-2y^2),{x,-2,2},{y,-3,3}]

Plot3D[Sin[x^2-2y^2],{x,-2,2},{y,-3,3},AxesLabel->{"x","y","z"}]

ContourPlot[Sin[x^2-2y^2],{x,-2,2},{y,-3,3}]

Plot3D[Exp[x^2-2y^2],{x,-2,2},{y,-3,3},AxesLabel->{"x","y","z"}]

ContourPlot[Exp[x^2-2y^2],{x,-2,2},{y,-3,3}]