Question

Solve by completing square method:
$x^2+8x+5$

Answer 1

$x^2+8x+5=0$

Third term = $(\frac{1}{2}\times$ coefficient of $x{)}^2={(\frac{1}{2}\times 8)}^2=16$

Adding on both sides.

$x^2+8x+16+5=16$

$x^2+2\cdot 4\cdot x+16=16-5$

$(x+4{)}^2=11$

Taking square root ,

$x+4=\pm \sqrt{11}$

$\therefore x=\sqrt{11}-4$ or $x=-\sqrt{11}-4$