\documentclass[11pt,openany]{book} 
\usepackage{amsthm,amsmath,amssymb}
\newtheoremstyle{shirin} {} {} {} {} {} {} {\newline} {}
\theoremstyle{shirin}
\usepackage{color}
\newtheorem{theorem}{قضیه}[chapter]
\newtheorem{definition}{تعریف}[chapter]
\newtheorem{example}{مثال}[chapter]
\newtheorem{attention}{نکته}[chapter]
\usepackage{circuitikz}
\usepackage{subfig}
\usepackage{graphicx}
\usepackage{sidecap}
\usepackage{float}
\usepackage{xepersian}
\settextfont{Yas}
\renewcommand{\baselinestretch}{1.5}\normalsize
\usetikzlibrary{arrows,snakes,backgrounds}

\begin{document}
\begin{minipage}{\linewidth}
\centering
\begin{minipage}{0.45\linewidth}
\begin{figure}[h]
\ctikzset{ bipoles/length=.98cm}
\begin{circuitikz}[scale =2.1, american]\draw
(0,1) node[anchor=east] {a}
to [short,*-,i^<=$i$] (1,1)
(0,2) node [anchor=east] {b}
to [short,*-,i=$i$] (1,2) -- (1,2.5) -- (2,2.5) -- (2,0.5) -- (1,0.5) -- (1,2)
(0,1.75) to [R,v= $V$,color=white] (0,1.25)
(1.25,1.5) to [R=$ N_{1}$ مدار] (1.75,1.5)
(0,1) -- (0,0.5) -- (-1.5,0.5) -- (-1.5,2.5) node [below right,text width=3cm,text centered,midway]
{
  مدار بقیه
}
to [short] (0,2.5) -- (0,2)
;\end{circuitikz}
\end{figure}
\end{minipage}
\hspace{0.05\linewidth}
\begin{minipage}{0.45\linewidth}
\[\begin{cases}
y_{1}&= k_{1}x_{1} + k_{2}x_{2} + \cdots + k_{n}x_{n}\\

\vdots\\

y_{n}&= L_{1}x_{1} + L_{2}x_{2} + \cdots + L_{n}x_{n}                  
\end{cases}
\]
\end{minipage}
\end{minipage}
\end{document}