\[\boxed{\mathbf{906\ (906)}\mathbf{.}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[\textbf{а)}\ верно.\]
\[\textbf{б)}\ неверно.\]
\[Контрпример:a = 0;\]
\[|a| = |0| = 0;\]
\[- |a| = - |0| = 0;\]
\[|a| = - |a|.\]