12x^2-24x-28=0

Solution for 12x^2-24x-28=0 equation:

12x^2-24x-28=0

a = 12; b = -24; c = -28;
Δ = b2-4ac
Δ = -242-4·12·(-28)
Δ = 1920
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:

$\sqrt{\Delta}=\sqrt{1920}=\sqrt{64*30}=\sqrt{64}*\sqrt{30}=8\sqrt{30}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-24)-8\sqrt{30}}{2*12}=\frac{24-8\sqrt{30}}{24}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-24)+8\sqrt{30}}{2*12}=\frac{24+8\sqrt{30}}{24}
$