Y=0.2x-2x^2

Solution for Y=0.2x-2x^2 equation:

=0.2Y-2Y^2

We move all terms to the left:

-(0.2Y-2Y^2)=0

We get rid of parentheses

2Y^2-0.2Y=0

a = 2; b = -0.2; c = 0;
Δ = b2-4ac
Δ = -0.22-4·2·0
Δ = 0.04
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-0.2)-\sqrt{0.04}}{2*2}=\frac{0.2-\sqrt{0.04}}{4}
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.2)+\sqrt{0.04}}{2*2}=\frac{0.2+\sqrt{0.04}}{4}
$