(a) Given that 2 +i is a complex root of the cubic polynomial $3 113:+2[l., determine the other two roots (without using a calculator]. (1]) Hence. (and without using a calculator) determine 3? f d3; 1:3 1122 + 20 (Hint: Use the result of part (a) to write 3:3 113 + 20 = (a: o}(3:2 + bx + c) for some a, E) and c, and use partial fractions.) (0) (i) Determine the general solution of the differential equation I E; A y" = 33111111\". 3: (Hint: Set in n = Maj.) y' and solve the resulting linear differential equation for