4. Does the following limit exist? :ry2 1 lim 5. Let 0, if sr2 < y < 2:r2 1, otherwise. Show that O) and O) exists, but f is not differentiable at (O, O). 4. Does the following limit exist? :ry2 1 lim 5. Let 0, if sr2 < y < 2:r2 1, otherwise. Show that O) and O) exists, but f is not differentiable at (O, O).