solve the equation by completing the square. round to the nearest hundredth if necessary. x^2+2x=8

Question

music0203 · Answer

@Michele_Laino @kidrah69

lυἶცἶ0210 · Answer

Well you have $\large x^2+2x= 8$ 

Now take b (2) and: $\large (\frac{b}{2})^2$ = $\large (\frac{2}{2})^2  $ =$1^2$ =1

So: 

$\Large x^2+2x\color{red}{+1}=8\color{red}{+1} $ 
Now add 1 to both sides to make it even, now condense: 

$\Large (x+1)^2=9 $ 

Subtract and set it equal to 0: 

$\Large (x+1)^2-9 =0$ and that should be it 


If you're solving then take the square root on both sides:

$\Large \sqrt{(x+1)^2} =\sqrt{9} $ 

$\Large (x+1)=\pm 3 $ 

Now solve for x: 
$\Large x=\pm3-1 $ 

:)