Plot3D[Sin[x]+Cos[y],{x,-4*Pi,4*Pi},{y,-4*Pi,4*Pi},
MeshFunctions->{#3&}(* nivåkurvor i grafen*)]

ContourPlot[Sin[x]+Cos[y],{x,-4*Pi,4*Pi},{y,-4*Pi,4*Pi}]

Plot3D[2x+3y,{x,-5,5},{y,-5,5}]

ContourPlot[2x+3y,{x,-5,5},{y,-5,5}]

ContourPlot3D[x^2+y^2+z^2,{x,-10,3},{y,-3,3},{z,-3,3},Contours->10]