80=x2+2x

Solution for 80=x2+2x equation:

80=x2+2x

We move all terms to the left:

80-(x2+2x)=0

We add all the numbers together, and all the variables

-(+x^2+2x)+80=0

We get rid of parentheses

-x^2-2x+80=0

We add all the numbers together, and all the variables

-1x^2-2x+80=0

a = -1; b = -2; c = +80;
Δ = b2-4ac
Δ = -22-4·(-1)·80
Δ = 324
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{324}=18$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-18}{2*-1}=\frac{-16}{-2}
=+8
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+18}{2*-1}=\frac{20}{-2}
=-10
$