x^2+20x=550

Solution for x^2+20x=550 equation:

x^2+20x=550

We move all terms to the left:

x^2+20x-(550)=0

a = 1; b = 20; c = -550;
Δ = b2-4ac
Δ = 202-4·1·(-550)
Δ = 2600
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:

$\sqrt{\Delta}=\sqrt{2600}=\sqrt{100*26}=\sqrt{100}*\sqrt{26}=10\sqrt{26}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-10\sqrt{26}}{2*1}=\frac{-20-10\sqrt{26}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+10\sqrt{26}}{2*1}=\frac{-20+10\sqrt{26}}{2}
$