a) Use the method of variation of parameters to solve fip dy - 39 + 2y dx? dx 1+ e2* (7 marks) b) An object of mass m is falling from a height h above a surface with velocity vo under the influence of gravity g with air resistance propor- tional to its velocity. If y(t) denotes the distance fall at time t in which the downward direction is assumed to be positive, then the motion of the objects satisfies the differential equation dy dy + k dt mg. dt2 Using the method of undetermined coefficients, solve this equation with initial conditions y = 0 and y vo when t = 0. (8 marks)