\[\boxed{\mathbf{887}.}\]
\[1)\ y = \log_{7}(5 - 2x)\]
\[5 - 2x > 0\]
\[- 2x > - 5\]
\[2x < 5\]
\[x < 2,5.\]
\[Ответ:\ \ x < 2,5.\]
\[2)\ y = \log_{2}\left( x^{2} - 2x \right)\]
\[x^{2} - 2x > 0\]
\[x(x - 2) > 0\]
\[x < 0;\text{\ \ }x > 2.\]
\[Ответ:\ \ x < 0;\ \ x > 2.\]