66x-3x^2=255

Solution for 66x-3x^2=255 equation:

66x-3x^2=255

We move all terms to the left:

66x-3x^2-(255)=0

a = -3; b = 66; c = -255;
Δ = b2-4ac
Δ = 662-4·(-3)·(-255)
Δ = 1296
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1296}=36$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(66)-36}{2*-3}=\frac{-102}{-6}
=+17
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(66)+36}{2*-3}=\frac{-30}{-6}
=+5
$