15.2 Limits and Continuity (graphs of functions for finding the limits)

Plot3D[(x^2-y^2)/(x^2 + y^2), {x, -1, 1}, {y, -1, 1}, AxesLabel -> {"x", "y", "z"}, PlotPoints -> 50]

Plot3D[x*y/(x^2 + y^2), {x, -1, 1}, {y, -1, 1}, AxesLabel -> {"x", "y", "z"}, PlotPoints -> 50]

Plot3D[x^2*y^2/(x^2 + y^2), {x, -1, 1}, {y, -1, 1}, AxesLabel -> {"x", "y", "z"}, PlotPoints -> 50]