TeX джерело:

{\;\;\left\{ \begin{array}{rcl}a_{11}x_1+a_{12}x_2+a_{13}x_3&=&b_1\\a_{21}x_1+a_{22}x_2+a_{23}x_3&=&b_2\\ a_{31}x_1+a_{32}x_2+a_{33}x_3&=&b_3 \end{array}\right.}