-12x^2+8x+396=0

Solution for -12x^2+8x+396=0 equation:

-12x^2+8x+396=0

a = -12; b = 8; c = +396;
Δ = b2-4ac
Δ = 82-4·(-12)·396
Δ = 19072
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{19072}=\sqrt{64*298}=\sqrt{64}*\sqrt{298}=8\sqrt{298}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(8)-8\sqrt{298}}{2*-12}=\frac{-8-8\sqrt{298}}{-24}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(8)+8\sqrt{298}}{2*-12}=\frac{-8+8\sqrt{298}}{-24}
$