Those questions are about explicit equations. (a) Explain why d = 1, y(0) = 1 cannot be solved. dt cos(t) (b) Find the general solutions to x' = sin(t)* 1 (c) Solve the IVP y = y(0) = 2 1+t2, (d) What's the Interval of Existence of sin(t)y' = cos(t), y() = 1?