2. 3. Use the particular solution method to solve y' Use the integrating factor method to solve 2xy' + y Which, if any, of the given differential equations is exact? Show how you test each equation, but do not solve them. a. (e sin(y) + 3y)dx (3x e sin(y) )dy 0 b. (3xy + y2)dx + (x + xy)dy 4. Which, if any, of the given differential equations is scale invariant? Show how you test each equation, but do not solve them. a. (dy/dx) (x + y)/x b. (3xy + y )dx + (x + xy)dy