Y=-125x^2+4000x

Solution for Y=-125x^2+4000x equation:

=-125Y^2+4000Y

We move all terms to the left:

-(-125Y^2+4000Y)=0

We get rid of parentheses

125Y^2-4000Y=0

a = 125; b = -4000; c = 0;
Δ = b2-4ac
Δ = -40002-4·125·0
Δ = 16000000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16000000}=4000$
$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4000)-4000}{2*125}=\frac{0}{250}
=0
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4000)+4000}{2*125}=\frac{8000}{250}
=32
$