Đi đến nội dung chính\(\require{cancel}\require{mathtools}\require{color}\require{boldsymbol}\newcommand{\N}{\mathbb{N}}
\newcommand{\pN}{\mathbb{N}^{*}}
\newcommand{\Z}{\mathbb{Z}}
\newcommand{\pZ}{\mathbb{Z}^{+}}
\newcommand{\mZ}{\mathbb{Z}^{-}}
\newcommand{\Q}{\mathbb{Q}}
\newcommand{\nQ}{\bar{\mathbb{Q}}}
\newcommand{\R}{\mathbb{R}}
\newcommand{\bs}[1]{\boldsymbol{#1}}
\newcommand{\mat}[1]{\begin{matrix}#1\end{matrix}}
\newcommand{\bmat}[1]{\begin{bmatrix}#1\end{bmatrix}}
\newcommand{\pmat}[1]{\begin{pmatrix}#1\end{pmatrix}}
\newcommand{\amat}[1]{\left\langle\begin{matrix}#1\end{matrix}\right\rangle}
\newcommand{\hvec}[1]{\bs{[}\begin{matrix}#1\end{matrix}\bs{]}}
\newcommand{\smat}[1]{\begin{smallmatrix}#1\end{smallmatrix}}
\newcommand{\sbmat}[1]{\begin{bsmallmatrix}#1\end{bsmallmatrix}}
\newcommand{\spmat}[1]{\begin{psmallmatrix}#1\end{psmallmatrix}}
\newcommand{\samat}[1]{\left\langle\begin{smallmatrix}#1\end{smallmatrix}\right\rangle}
\newcommand{\shvec}[1]{\bs{[}\begin{smallmatrix}#1\end{smallmatrix}\bs{]}}
\newcommand{\lt}{<}
\newcommand{\gt}{>}
\newcommand{\amp}{&}
\definecolor{fillinmathshade}{gray}{0.9}
\newcommand{\fillinmath}[1]{\mathchoice{\colorbox{fillinmathshade}{$\displaystyle \phantom{\,#1\,}$}}{\colorbox{fillinmathshade}{$\textstyle \phantom{\,#1\,}$}}{\colorbox{fillinmathshade}{$\scriptstyle \phantom{\,#1\,}$}}{\colorbox{fillinmathshade}{$\scriptscriptstyle\phantom{\,#1\,}$}}}
\)
