\[\boxed{Страница\ 23.}\]
\[\boxed{\mathbf{1.}}\]
\[\boxed{\mathbf{2.}}\]
\[\boxed{\mathbf{3.}}\]
\[3000 < 5255 - 1849 < 5000\]
\[3000 < 3406 < 5000.\]
\[\boxed{\mathbf{4.}}\]
\[\textbf{а)}\ x > 8\]
\[x = \left\{ 9;10;11;12;\ldots \right\}.\]
\[\textbf{б)}\ y \leq 5\]
\[y = \left\{ 0;1;2;3;4;5 \right\}.\]
\[\textbf{в)}\ 1 \leq k < 6\]
\[k = \left\{ 1;2;3;4;5 \right\}.\]
\[\boxed{\mathbf{5.}}\]