391=x2+6x

Solution for 391=x2+6x equation:

391=x2+6x

We move all terms to the left:

391-(x2+6x)=0

We add all the numbers together, and all the variables

-(+x^2+6x)+391=0

We get rid of parentheses

-x^2-6x+391=0

We add all the numbers together, and all the variables

-1x^2-6x+391=0

a = -1; b = -6; c = +391;
Δ = b2-4ac
Δ = -62-4·(-1)·391
Δ = 1600
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1600}=40$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-40}{2*-1}=\frac{-34}{-2}
=+17
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+40}{2*-1}=\frac{46}{-2}
=-23
$