\[\boxed{\mathbf{836}.}\]
\[1)\log_{2}x = - x + 1\]
\[x = 1.\]
\[2)\log_{\frac{1}{2}}x = 2x - 5\]
\[x = 2.\]
\[3)\lg x = \sqrt{x}\]
\[нет\ корней.\]
\[4)\lg x = 2^{- x}\]
\[x \approx 1,87.\]