Solution of $${(x + y)^2}{{dy} \over {dx}} = {a^2}$$ ('a' belong a constant) is

The integrating factor of the first order differential equation $${x^2}({x^2} - 1){{dy} \over {dx}} + x({x^2} + 1)y = {x^2} - 1$$ is

If the solution of the differential equation $$x{{dy} \over {dx}} + y = x{e^x}\,be\,xy = {e^x}\phi (x) + C$$, then $$\phi$$(x) is equal to

General solution of $$y{{dy} \over {dx}} + b{y^2} = a\cos x,0 < x < 1$$ is