Y=0.04x2+1.2x

Solution for Y=0.04x2+1.2x equation:

=0.04Y^2+1.2Y

We move all terms to the left:

-(0.04Y^2+1.2Y)=0

We get rid of parentheses

-0.04Y^2-1.2Y=0

a = -0.04; b = -1.2; c = 0;
Δ = b2-4ac
Δ = -1.22-4·(-0.04)·0
Δ = 1.44
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{-(-1.2)-\sqrt{1.44}}{2*-0.04}=\frac{1.2-\sqrt{1.44}}{-0.08}
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1.2)+\sqrt{1.44}}{2*-0.04}=\frac{1.2+\sqrt{1.44}}{-0.08}
$