Question

Factorize:

$7(x-2y{)}^2-25(x-2y)+12$

Answer 1

$7(x-2y{)}^2-25(x-2y)+12$
Let $x-2y=a$
Now, $7a^2-25a+12$
$\because 7\times 12=84$
$\therefore 84=-21\times (-4)$
So, $-25=-21-4$
$=7a^2-21a-4a+12$
$=7a(a-3)-4(a-3)$
$=(a-3)(7a-4)$
$=(x-2y-3)(7x-14y-4)$