0=X^2+4x-336

Solution for 0=X^2+4x-336 equation:

0=X^2+4X-336

We move all terms to the left:

0-(X^2+4X-336)=0

We add all the numbers together, and all the variables

-(X^2+4X-336)=0

We get rid of parentheses

-X^2-4X+336=0

We add all the numbers together, and all the variables

-1X^2-4X+336=0

a = -1; b = -4; c = +336;
Δ = b2-4ac
Δ = -42-4·(-1)·336
Δ = 1360
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:

$\sqrt{\Delta}=\sqrt{1360}=\sqrt{16*85}=\sqrt{16}*\sqrt{85}=4\sqrt{85}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-4\sqrt{85}}{2*-1}=\frac{4-4\sqrt{85}}{-2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+4\sqrt{85}}{2*-1}=\frac{4+4\sqrt{85}}{-2}
$