\( \newcommand{\eq}[1]{\begin{array}{rrl@{\quad}l}#1\end{array}} \newcommand{\D}{\displaystyle} \newcommand{\LR}{\Leftrightarrow} \newcommand{\m}[1]{\begin{pmatrix}#1\end{pmatrix}} \) \( \newcommand{\tb}[1]{{\color{blue}{#1}}} \newcommand{\tr}[1]{{\color{red}{#1}}} \newcommand{\tg}[1]{{\color{green}{#1}}} \newcommand{\N}{{\mathbb N }} \newcommand{\R}{{\mathbb R }} \newcommand{\Z}{{\mathbb Z }} \newcommand{\Q}{{\mathbb Q }} \newcommand{\C}{{\mathbb C }} \)