# How do you solve 6x^2 + 36x + 18 = 0 using completing the square?

Jun 11, 2015

First thing to notice, is that everything can be divided by 6

#### Explanation:

So the equation becomes:
${x}^{2} + 6 x + 3 = 0$

Completing the square is you take half of the number with $x$ and square it, which would be ${x}^{2} + 6 x + 9$, but to even out with the $3$ you've got, you write $3 = 9 - 6$:
${x}^{2} + 6 x + 9 - 6 = 0 \to$
${\left(x + 3\right)}^{2} - 6 = 0 \to {\left(x + 3\right)}^{2} = 6 \to$
$x + 3 = \pm \sqrt{6} \to x = - 3 \pm \sqrt{6}$