42x^2+264x-72=0

Solution for 42x^2+264x-72=0 equation:

42x^2+264x-72=0

a = 42; b = 264; c = -72;
Δ = b2-4ac
Δ = 2642-4·42·(-72)
Δ = 81792
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:

$\sqrt{\Delta}=\sqrt{81792}=\sqrt{576*142}=\sqrt{576}*\sqrt{142}=24\sqrt{142}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(264)-24\sqrt{142}}{2*42}=\frac{-264-24\sqrt{142}}{84}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(264)+24\sqrt{142}}{2*42}=\frac{-264+24\sqrt{142}}{84}
$