1: Exactness test. If exact, solve the diff. eq.

(2r^2 3)dr + (3r^2^2 3r + 4) d = 0

2: Solve the following differential equation by the separation of variables.

x^2 dx + y(x 1)dy = 0

3: Solve the following linear ODE using annihilator method.

d^3y(x)/dx^3 3 d^2y(x)/dx^2 + 4 y(x) = 6 + 80cos2x