# Quadratic Equations by Completing the Square

#### App

Hi,
I'm working on this equation where (b/2)^2 = 8/2=4^2=16. However, I'm stuck where I think I need to square both sides, as you can see a purple star there. I also scratchy on how to factor x^2+4x+8? which the answer becomes in the end is in red. -2 plus or minus sq of 14

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#### skeeter

Math Team
$2x^2+8x+1=0$

$2x^2+8x = -1$

$x^2+4x=-\dfrac{1}{2}$

$x^2+4x+4 = -\dfrac{1}{2} +4$

$(x+2)^2=\dfrac{7}{2}$

$x+2= \pm \sqrt{\dfrac{7}{2}}$

$x = -2 \pm \dfrac{\sqrt{14}}{2} = \dfrac{-4 \pm \sqrt{14}}{2}$

Thank you!

#### Country Boy

Math Team
Your basic error was that you did not have $$\displaystyle x^2+ 8x+ 1$$ that you are trying to make a "complete square", you have $$\displaystyle 2x^2+ 8x+ 1$$ and that "2" multiplying $$\displaystyle x^2$$ makes all the difference. skeeter took care of that by first dividing the equation by 2.