Задача 3.

Show that for any $a$, $b$ and $c$ such that $a\cdot b\cdot c\ne0$, we have 1) $GCM(a,b,c) = GCD(a,НОД(b,c)) = GCD(GCD(a,b),c)$; 2) $LCM(a,b,c) = \frac{|abc|\cdot GCD(a,b,c)}{GCD(a,b)\cdot GCD(b,c)\cdot GCD(a,c)}$.