80+2x=x^2

Solution for 80+2x=x^2 equation:

80+2x=x^2

We move all terms to the left:

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

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