Question

Find the roots of $x^2-4x-8=0$ by the method of completing square.

Answer 1

$x^2-4x-8=0$

$\Rightarrow x^2-4x+4-12=0$

$\Rightarrow {(x-2)}^2-{\left(\sqrt{12}\right)}^2=0$

$\Rightarrow (x-2+\sqrt{12})(x-2-\sqrt{12})=0$

$\therefore x=2-\sqrt{12};x=2+\sqrt{12}$