5. [12 marks] Find (if possible) the general solution of each of the following 2nd-order ODEs by trying y = ext. If you can't find a solution, give a reason. (a) y" - 5y' + 6y = 0 (b) y" +xy' tell=0 (c) =y" + by' + 18y =0 In part (c), find the solution with initial conditions y (0) = 1, y' (0) = 0