ParametricPlot3D[{2+u,2*u,2},{u,0,2},AxesLabel->{x,y,z}]

Plot3D[x*E^y,{x,2,3},{y,0,0.1},AxesLabel->{x,y,z}]

ContourPlot[x*E^y,{x,1,2},{y,-2,0}]

ContourPlot3D[{x*E^y==z}, {x,0,3},{y,0,2},{z,0,15}, MeshFunctions->{#3&}, Axes->True,AxesLabel->{x,y,z}]