\[\boxed{\text{680.}\text{\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]
\[\textbf{а)}\ (x - 3)(y - 3) = 0\]
\[\textbf{б)}\ (x + 2)(y + 2) = 0\]
\[\textbf{в)}\ (y + 2)(y - 2) = 0\]
\[\textbf{г)}\ (x - 4)(x + 2) = 0\ \]