P(x)=-3x^2+72x

Solution for P(x)=-3x^2+72x equation:

(P)=-3P^2+72P

We move all terms to the left:

(P)-(-3P^2+72P)=0

We get rid of parentheses

3P^2-72P+P=0

We add all the numbers together, and all the variables

3P^2-71P=0

a = 3; b = -71; c = 0;
Δ = b2-4ac
Δ = -712-4·3·0
Δ = 5041
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$P_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$P_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5041}=71$
$P_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-71)-71}{2*3}=\frac{0}{6}
=0
$
$P_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-71)+71}{2*3}=\frac{142}{6}
=23+2/3
$