P(x)=-15x^2+600x+60

Solution for P(x)=-15x^2+600x+60 equation:

(P)=-15P^2+600P+60

We move all terms to the left:

(P)-(-15P^2+600P+60)=0

We get rid of parentheses

15P^2-600P+P-60=0

We add all the numbers together, and all the variables

15P^2-599P-60=0

a = 15; b = -599; c = -60;
Δ = b2-4ac
Δ = -5992-4·15·(-60)
Δ = 362401
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$P_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$P_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$P_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-599)-\sqrt{362401}}{2*15}=\frac{599-\sqrt{362401}}{30}
$
$P_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-599)+\sqrt{362401}}{2*15}=\frac{599+\sqrt{362401}}{30}
$