Question

Solve:
$x^2-21x+108=0$

Answer 1

$x^2-21x+108=0$

$\Rightarrow x^2-12x-9x+108=0$

$\Rightarrow (x-12)(x-9)=0$

$\Rightarrow x-12=0$ OR $x-9=0$

$\Rightarrow x=12$ OR $x=9$