parentheses latex code example

Example 1: big brackets latex

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

Example 2: brackets equation latex

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{equation}
  D_{it} =
    \begin{cases}
      1 & \text{if bank $i$ issues ABs at time $t$}\\
      2 & \text{if bank $i$ issues CBs at time $t$}\\
      0 & \text{otherwise}
    \end{cases}       
\end{equation}
\end{document}

Example 3: latex parentheses

\left(\sum_i^n\right)