3. Solve the equation $\frac{\sqrt{(-x)^{2}}+(\sqrt{-x})^{2}}{x^{2}+(-x)^{2}}=\frac{1}{2016}$

ANSWER: $x=-2016$.
Solution: Note that $\mathrm{x}<0$ from the domain, we can represent the equation as $\frac{-2 x}{2 x^{2}}=\frac{1}{2016}$.