Sorry for my bad English.
How can I removing space between bracket and array environment and obtained results as used cases environment.
Thank you very much!
I use code
\[\left\{\begin{array}{l} x + y = 1\\ x - y = 2 \end{array}\right.\]
\[\begin{cases} x+y=1 \\ x-y=2\end{cases}.\]




\left\{, add\mkern-8muor (approximate)\!\!\!. It is one reason whyamsmathis preferred toarray.\begin{array}{@{}l}?