verify that the pair x(t), y(t) is a solution to the given system. Sketch the trajectory of the given solution in the phase plane. dx/dt = 3y^3 , dy/dt = y ; x(t) =e^3t , y(t) = e^t dx/dt = 1 , dy/dt = 3x^2 ; x(t) = t + 1, y(t) = t^3 + 3t^2 +3t