\[\boxed{\text{1216.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
\[\textbf{а)}\ y + |y| = x\]
\[при\ y \geq 0:\]
\[y + y = x\]
\[2y = x\]
\[y = \frac{1}{2}\text{x.}\]
\[при\ y < 0:\]
\[y - y = x\]
\[x = 0.\]
\[\textbf{б)}\ y = x|y|\]
\[при\ y > 0:\]
\[y = xy\]
\[x = 1.\]
\[при\ y < 0:\]
\[y = - xy\]
\[x = - 1.\]
\[при\ y = 0:\]
\[x - любое\ число.\]