(6) The initial value problem dy dy dy + y(y +0.5y) = sin(2.01 t), y(0) = 0, (0) = 1 dt2 dt dt is a model problem for forced nonlinear oscillators. (a) Express the model as an initial value problem for a first order system of equations. (b) Carry out one step of Heun's method on your first order system, with step size h = 0.1, to estimate y(0.1). %3D