$\begin{array}{1 1}\large\frac{x^2}{5}+\frac{y^2}{5}\normalsize =1\\\large\frac{x^2}{5}-\frac{y^2}{5}\normalsize =1\\\large\frac{x^2}{5}+\frac{y^2}{5}\normalsize =-1\\\large\frac{x^2}{5}-\frac{y^2}{5}\normalsize =-1\end{array} $