\[\boxed{\text{1217.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
\[\textbf{а)}\ y = |x| - 3\]
\[при\ x \geq 0:\]
\[y = x - 3.\]
\[при\ x < 0:\]
\[y = - x - 3\]
\[\textbf{б)}\ y = 4 - |x|\]
\[при\ x \geq 0:\]
\[y = 4 - x.\]
\[при\ x < 0:\]
\[y = 4 + x\]