Y=-0,04x^2+0,6x+1.8

Solution for Y=-0,04x^2+0,6x+1.8 equation:

=-0.04Y^2+0.6Y+1.8

We move all terms to the left:

-(-0.04Y^2+0.6Y+1.8)=0

We get rid of parentheses

0.04Y^2-0.6Y-1.8=0

a = 0.04; b = -0.6; c = -1.8;
Δ = b2-4ac
Δ = -0.62-4·0.04·(-1.8)
Δ = 0.648
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{-(-0.6)-\sqrt{0.648}}{2*0.04}=\frac{0.6-\sqrt{0.648}}{0.08}
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-0.6)+\sqrt{0.648}}{2*0.04}=\frac{0.6+\sqrt{0.648}}{0.08}
$