x2+6x=391

Solution for x2+6x=391 equation:

x2+6x=391

We move all terms to the left:

x2+6x-(391)=0

We add all the numbers together, and all the variables

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