What is the order of the differential equation $${{dx} \over {dy}} + \int {y\,dx = {x^3}} $$ ?

Which one of the following differential equations represents the family of straight lines, which are at unit distance from the origin ?

What is the order and degree, respectively of the differential equation whose solution is $$y = cx + {c^2} - 3{c^{3/2}} + 2$$, where c is a parameter?

The general solution of $${{dy} \over {dx}} = {{ax + h} \over {by + k}}$$ represents a circle only when