Đáp án:
$\begin{array}{l}
1)\left\{ \begin{array}{l}
x\sqrt 5 - \left( {1 + \sqrt 3 } \right)y = 1\\
\left( {1 - \sqrt 3 } \right)x + y\sqrt 5 = 1
\end{array} \right.\\
\Rightarrow \left\{ \begin{array}{l}
\left( {1 - \sqrt 3 } \right).\sqrt 5 .x - \left( {1 + \sqrt 3 } \right).\left( {1 - \sqrt 3 } \right)y = 1 - \sqrt 3 \\
\left( {1 - \sqrt 3 } \right).\sqrt 5 x + 5y = \sqrt 5
\end{array} \right.\\
\Rightarrow \left\{ \begin{array}{l}
5y + \left( {1 - \sqrt 3 } \right)y = \sqrt 5 - 1 + \sqrt 3 \\
x\sqrt 5 - \left( {1 + \sqrt 3 } \right)y = 1
\end{array} \right.\\
\Rightarrow \left\{ \begin{array}{l}
y = \frac{{\sqrt 5 + \sqrt 3 - 1}}{{6 - \sqrt 3 }}\\
x = 0,849
\end{array} \right.\\
2)\left\{ \begin{array}{l}
\left| x \right| + 4\left| y \right| = 18\\
3\left| x \right| + \left| y \right| = 10
\end{array} \right.\\
\Rightarrow \left\{ \begin{array}{l}
3\left| x \right| + 12\left| y \right| = 54\\
3\left| x \right| + \left| y \right| = 10
\end{array} \right.\\
\Rightarrow \left\{ \begin{array}{l}
11\left| y \right| = 44\\
\left| x \right| = 18 - 4\left| y \right|
\end{array} \right.\\
\Rightarrow \left\{ \begin{array}{l}
\left| y \right| = 4\\
\left| x \right| = 2
\end{array} \right.\\
\Rightarrow \left( {x;y} \right) = \left( { \pm 2; \pm 4} \right)
\end{array}$
