Question 17
Let $\mathcal{D}$ be the set of complex numbers that can be written in the form $a+b \sqrt{-13}$, with $a, b$ integers. The number $14=14+0 \sqrt{-13}$ can be written as a product of two elements of $\mathcal{D}$: $14=2 \cdot 7$. Express 14 as a product of two elements of $\mathcal{D}$ in all possible ways.