\begin{gathered}\left \{ \begin{array}{lcl} {{x-y=3,} \\ {x+y=6;}} \end{array} \right.\Leftrightarrow\left \{ \begin{array}{lcl} {{2x=9,} \\ {x+y=6;}} \end{array} \right.\Leftrightarrow\left \{ \begin{array}{lcl} {{x=4,5,} \\ {y=6-4,5;}} \end{array} \right.\Leftrightarrow \left \{ \begin{array}{lcl} {{x=4,5,} \\ {y=1,5.}} \end{array} \right.\end{gathered}​

jeneksoul1997    3   04.05.2021 07:56    1