14=2x^2-4x-8

Solution for 14=2x^2-4x-8 equation:

14=2x^2-4x-8

We move all terms to the left:

14-(2x^2-4x-8)=0

We get rid of parentheses

-2x^2+4x+8+14=0

We add all the numbers together, and all the variables

-2x^2+4x+22=0

a = -2; b = 4; c = +22;
Δ = b2-4ac
Δ = 42-4·(-2)·22
Δ = 192
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:

$\sqrt{\Delta}=\sqrt{192}=\sqrt{64*3}=\sqrt{64}*\sqrt{3}=8\sqrt{3}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-8\sqrt{3}}{2*-2}=\frac{-4-8\sqrt{3}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+8\sqrt{3}}{2*-2}=\frac{-4+8\sqrt{3}}{-4}
$