\[\boxed{\text{1215.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
\[\textbf{а)}\ (x - 2)(y + 3) = 0\]
\[x - 2 = 0\]
\[x = 2\]
\[y + 3 = 0\]
\[y = - 3\]
\[\textbf{б)}\ x^{2} + xy = 0\]
\[x(x + y) = 0\]
\[x = 0;\ \ \ \ \ y = - x\]