841=2x^2+2x

Solution for 841=2x^2+2x equation:

841=2x^2+2x

We move all terms to the left:

841-(2x^2+2x)=0

We get rid of parentheses

-2x^2-2x+841=0

a = -2; b = -2; c = +841;
Δ = b2-4ac
Δ = -22-4·(-2)·841
Δ = 6732
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{6732}=\sqrt{36*187}=\sqrt{36}*\sqrt{187}=6\sqrt{187}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-6\sqrt{187}}{2*-2}=\frac{2-6\sqrt{187}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+6\sqrt{187}}{2*-2}=\frac{2+6\sqrt{187}}{-4}
$