Inserting braces in a brace

Question

I don’t know how can I ensert the right braces using latex...

Any help is appreciated...

Answer 1

Quick and dirty

\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{equation*}
\left\{
\begin{aligned}
\left.
\begin{aligned}
a\\
b
\end{aligned}
\right\}\\
\left.
\begin{aligned}
a\\
b
\end{aligned}
\right\}
\end{aligned}
\right.
\end{equation*}
\end{document}

Answer 2

You can nest rcases (from mathtools) inside a regular cases:

\documentclass{article}

\usepackage{mathtools,eqparbox}

\begin{document}

\[
  \begin{cases}
    \begin{rcases}
      \eqmakebox[LHS][r]{$\dfrac{\mathrm{d}G(t)}{\mathrm{d}t}$} =
        \eqmakebox[RHS][l]{$G_{\text{in}} - \sigma_2 G - a \biggl( c + \dfrac{m I}{n + I} \biggr) G + b$} \\
      \eqmakebox[LHS][r]{$\dfrac{\mathrm{d}I(t)}{\mathrm{d}t}$} =
        \dfrac{\sigma_1 G^2}{\alpha_1^2 + G^2} - d_i I(t)
    \end{rcases} \quad G < L_G \text{ or } I > I_C, \\
    \begin{rcases}
      \eqmakebox[LHS][r]{$G(T^+)$} =
        \eqmakebox[RHS][l]{$G(t)$} \\
      \eqmakebox[LHS][r]{$I(t^+)$} =
        I(t) + \sigma
    \end{rcases} \quad G = L_G \text{ and } I \leq I_C
  \end{cases}
\]

\end{document}

The addition of eqparbox is purely for aesthetic reasons; horizontal alignment of the equations inside and across the rcases environments. One could have achieved something similar using aligned.