\[|x| + 2|y| = 6\]
\[|x| = 6 - 2|y|\]
\[Ромб,\ со\ стороной\ \]
\[a = \sqrt{9 + 36} = \sqrt{45} = 3\sqrt{5}.\]
\[P = 4 \cdot 3\sqrt{5} = 12\sqrt{5}.\]
\[Ответ:ромб,\ 12\sqrt{5}.\]