ពៅ ពេជ្រពុទ្ធិពង្ស

\documentclass{article}
\usepackage{tikz}
\usepackage{mathtools}
\usepackage{euler}
\everymath{\displaystyle}
\begin{document}

$\begin{cases}
x'&=\frac{\Delta D_{x'}}{D} =\frac{\begin{vmatrix}
1&-y\\ 0&x
\end{vmatrix}}{x^2+y^2}\\
y'&=\frac{\Delta D_{y'}}{D} =\frac{\begin{vmatrix}
x&1\\ x&0
\end{vmatrix}}{x^2+y^2}
\end{cases} \\
\begin{matrix}
x'&=\frac{\Delta D_{x'}}{D} =\frac{\begin{vmatrix}
1&-y\\ 0&x
\end{vmatrix}}{x^2+y^2}=\frac{x}{ x^2+y^2}\\
\tikz{\node[overlay] at (-.2,.7) {$\left\{\rule{0pt}{.95cm}\right.$};}
y'&=\frac{\Delta D_{y'}}{D} =\frac{\begin{vmatrix}
x&1\\ x&0
\end{vmatrix}}{x^2+y^2}=\frac{-y}{ x^2+y^2}
\end{matrix}$
\end{document}

👉 ពៅ ពេជ្រពុទ្ធិពង្ស

\documentclass{article}
\usepackage{tikz}
\def\checkmark{\tikz\fill[scale=0.4,left color=red](0,.35) -- (.25,0) -- (1,.7) -- (.25,.15) -- cycle;}
\newcommand{\Check}{\begin{tikzpicture}
\draw[blue,thick] (0,0)rectangle(.2,.2);
\fill[scale=0.3,left color=teal!50!blue,overlay,yshift=.1cm,xshift=.12cm,draw=white,line width=0.2pt](0,.35) -- (.25,0) -- (1,.7) -- (.25,.15) -- cycle;
\end{tikzpicture}}
\begin{document}
This is a \checkmark checkmark.\Check
\end{document}

👉 ពៅ ពេជ្រពុទ្ធិពង្ស