P=-0.3x^2+36x-1040

Solution for P=-0.3x^2+36x-1040 equation:

=-0.3P^2+36P-1040

We move all terms to the left:

-(-0.3P^2+36P-1040)=0

We get rid of parentheses

0.3P^2-36P+1040=0

a = 0.3; b = -36; c = +1040;
Δ = b2-4ac
Δ = -362-4·0.3·1040
Δ = 48
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$P_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$P_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{48}=\sqrt{16*3}=\sqrt{16}*\sqrt{3}=4\sqrt{3}$
$P_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-36)-4\sqrt{3}}{2*0.3}=\frac{36-4\sqrt{3}}{0.6}
$
$P_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-36)+4\sqrt{3}}{2*0.3}=\frac{36+4\sqrt{3}}{0.6}
$