2. Are the following differential equations exact? If not, try t, y, and y^2 as possible integrating factors.
(a) 2(t^3 + 1) dy + 3yt^2 dt = 0
(b) 4y^3t dy + (2y^4 + 3t) dt = 0
3. By applying the four-step procedure to the general exact differential equation M dy + N dt = 0, derive the following formula for the general solution of an exact differential equation:
∫ M dy + ∫ N dt - ∫ (∂/∂t ∫ M dy) dt = c