\[\boxed{\mathbf{864}.}\]
\[1)\ y = \lg(3x - 2)\]
\[3x - 2 > 0\]
\[3x > 2\ \]
\[x > \frac{2}{3}\]
\[Ответ:\ \ x > \frac{2}{3}.\]
\[2)\ y = \log_{2}(7 - 5x)\]
\[7 - 5x > 0\]
\[5x < 7\]
\[x < 1,4\]
\[Ответ:\ \ x < 1,4.\]
\[3)\ y = \log_{\frac{1}{2}}\left( x^{2} - 2 \right)\]
\[x^{2} - 2 > 0\]
\[x^{2} > 2\]
\[x < - \sqrt{2}\ ;\text{\ \ }x > \sqrt{2}.\]
\[Ответ:\ \ x < - \sqrt{2};\ x > \sqrt{2}.\]
\[4)\ y = \log_{7}{(4 - x^{2})}\]
\[4 - x^{2} > 0\]
\[x^{2} - 4 < 0\]
\[(x + 2)(x - 2) < 0\]
\[- 2 < x < 2\]
\[Ответ:\ \ - 2 < x < 2.\]