Limits Continuity and Differentiability

$$f$$ is defined in $$\left[ { - 5,5} \right]$$ as $$f\left( x \right) = x$$ if $$x$$ is rational $$\,\,\,\,\,\,\,\,\,\,\,\,\,$$ $$= - x$$ if $$x$$ is irrational. Then