2. Solve by hand for a few time steps the numerical scheme (2) for un = Uxx, With u(x, 0) = 0, with 0 0 0 01 210 0 00 and with the starting scheme (6). (a) First use At = 1 and Ax = 0.5. (b) Then use At = 1 and Ax = 1. (c) Compare your answers to parts (a) and (b)