14x^2+28x-84=0

Solution for 14x^2+28x-84=0 equation:

14x^2+28x-84=0

a = 14; b = 28; c = -84;
Δ = b2-4ac
Δ = 282-4·14·(-84)
Δ = 5488
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:

$\sqrt{\Delta}=\sqrt{5488}=\sqrt{784*7}=\sqrt{784}*\sqrt{7}=28\sqrt{7}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-28\sqrt{7}}{2*14}=\frac{-28-28\sqrt{7}}{28}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+28\sqrt{7}}{2*14}=\frac{-28+28\sqrt{7}}{28}
$