big brackets latex

1\[ 
2F = G \left( \frac{m_1 m_2}{r^2} \right)
3\]
4

1\documentclass{article}
2\usepackage{amsmath}
3\begin{document}
4\begin{equation}
5  D_{it} =
6    \begin{cases}
7      1 & \text{if bank $i$ issues ABs at time $t$}\\
8      2 & \text{if bank $i$ issues CBs at time $t$}\\
9      0 & \text{otherwise}
10    \end{cases}       
11\end{equation}
12\end{document}

1\left[ *Your formula here* \right]
2%Using left and right makes the brackets adapt dynamically to your needs