336=2x^2+4x

Solution for 336=2x^2+4x equation:

336=2x^2+4x

We move all terms to the left:

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

We get rid of parentheses

-2x^2-4x+336=0

a = -2; b = -4; c = +336;
Δ = b2-4ac
Δ = -42-4·(-2)·336
Δ = 2704
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2704}=52$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-52}{2*-2}=\frac{-48}{-4}
=+12
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+52}{2*-2}=\frac{56}{-4}
=-14
$