Y=-0.008x^2+10x+2400

Solution for Y=-0.008x^2+10x+2400 equation:

=-0.008Y^2+10Y+2400

We move all terms to the left:

-(-0.008Y^2+10Y+2400)=0

We get rid of parentheses

0.008Y^2-10Y-2400=0

a = 0.008; b = -10; c = -2400;
Δ = b2-4ac
Δ = -102-4·0.008·(-2400)
Δ = 176.8
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{-(-10)-\sqrt{176.8}}{2*0.008}=\frac{10-\sqrt{176.8}}{0.016}
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+\sqrt{176.8}}{2*0.008}=\frac{10+\sqrt{176.8}}{0.016}
$