Y=-20x2+2800x

Solution for Y=-20x2+2800x equation:

=-20Y^2+2800Y

We move all terms to the left:

-(-20Y^2+2800Y)=0

We get rid of parentheses

20Y^2-2800Y=0

a = 20; b = -2800; c = 0;
Δ = b2-4ac
Δ = -28002-4·20·0
Δ = 7840000
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{7840000}=2800$
$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2800)-2800}{2*20}=\frac{0}{40}
=0
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2800)+2800}{2*20}=\frac{5600}{40}
=140
$