\[\boxed{\text{1219.\ }\text{еуроки}\text{-}\text{ответы}\text{\ }\text{на}\text{\ }\text{пятёрку}}\]
\[\textbf{а)}\ y = \frac{1}{|x| - x}\]
\[|x| - x \neq 0\]
\[|x| \neq x\]
\[x < 0\]
\[\textbf{б)}\ y = \frac{1}{|x| + x}\]
\[|x| + x \neq 0\]
\[|x| \neq - x\]
\[x > 0\]