P=-60x^2+120x

Solution for P=-60x^2+120x equation:

=-60P^2+120P

We move all terms to the left:

-(-60P^2+120P)=0

We get rid of parentheses

60P^2-120P=0

a = 60; b = -120; c = 0;
Δ = b2-4ac
Δ = -1202-4·60·0
Δ = 14400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$P_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$P_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{14400}=120$
$P_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-120)-120}{2*60}=\frac{0}{120}
=0
$
$P_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-120)+120}{2*60}=\frac{240}{120}
=2
$