16. The solution of the wave equation urr = -Utt, 0 0, which satisfies the boundary conditions u(0, t) = 0 and u(3, t) = 0, and the initial conditions u(x, 0) - 2sin(7x) - sin () and ut(x, 0) = sin(x) - 2 sin(3xx), is u(x, t) = _sin ("a2 ) an cos (2nut 3 + bnsin 2nat n= 1 where (a) a1 = -1, a3 = 2, b3 = 1, bg = -2, an - bn = 0 otherwise (b) a1 = -1, a2 = 2, b3 = 1, bg = -2, an = bn = 0 otherwise 1 (cal = -1, a3 = 2, 63 = -, bg = 2 TT 37T' an = bn =0 otherwise (d) a1 = -1, a3 = 2, b3 3 - 271, bg = -37, an = bn = 0 otherwise (e) None of the above 17. The solution u(x, y) of Laplace's equation urr + Uyy = 0 within the rectangular region 0 an sinh no (3, - 20) ] sin ("by ) n= 1 (e) u(x, y) = ax + By + yay to