dR dt = a(3 R) = :Select one dt dR (3-R) .a a dt = (3 RldR .b a dR = (3 (3 R)dt .c = a adt (3 R)dR .d 1 = = y = u 3 where u = u(x) then :Select one 4 - u u(x) .a 3 ) 0.b 2 - U 3 .C - 3 u du od dx