-3x2+72x-285=0

Solution for -3x2+72x-285=0 equation:

-3x^2+72x-285=0

a = -3; b = 72; c = -285;
Δ = b2-4ac
Δ = 722-4·(-3)·(-285)
Δ = 1764
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1764}=42$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(72)-42}{2*-3}=\frac{-114}{-6}
=+19
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(72)+42}{2*-3}=\frac{-30}{-6}
=+5
$