3. (a) Determine the general solution of the differential equation = ICOS 7x. (Hint: Set v = y' and solve the resulting linear differential equation for v = v(x).) (b) (i) Given that -1 + 47 is a complex root of the cubic polynomial a + 13x - 34, determine the other two roots (without using a calculator). (ii) Hence, (and without using a calculator) determine 25 dx. r3 + 13x - 34 (Hint: Use the result of part (a) to write r + 13x - 34 = (x - a)(x' + br + c) for some a, b and c, and use partial fractions.) (8 + (3+9) = 20 marks)