V=-180x^2+2000x

Solution for V=-180x^2+2000x equation:

=-180V^2+2000V

We move all terms to the left:

-(-180V^2+2000V)=0

We get rid of parentheses

180V^2-2000V=0

a = 180; b = -2000; c = 0;
Δ = b2-4ac
Δ = -20002-4·180·0
Δ = 4000000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$V_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$V_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4000000}=2000$
$V_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2000)-2000}{2*180}=\frac{0}{360}
=0
$
$V_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2000)+2000}{2*180}=\frac{4000}{360}
=11+1/9
$