The function f(x) which satisfies $$f(x) = f( - x) = {{f'(x)} \over x}$$ is given by

The degree of the differential equation $${\left[ {1 + {{\left( {{{dy} \over {dx}}} \right)}^2}} \right]^{5/3}} = {{{d^2}y} \over {d{x^2}}}$$ is

The differential equation of all parabolas whose axes are parallel to y-axis is

The solution of the differential equation $${{dy} \over {dx}} = {e^{y + x}} + {e^{y - x}}$$ is