Factorize each of the following expression:

$a(a-2 b-c)+2 b c=a^{2}-2 a b-a c+2 b c$

$=\left(a^{2}-a c\right)+(2 b c-2 a b)$      [Regrouping the terms]

$=a(a-c)+2 b(c-a)$

$=a(a-c)-2 b(a-c)$      $[\because(c-a)=-(a-c)]$

$=(a-2 b)(a-c)$           $[$ Taking $(a-c)$ as the common factor $]$