640=2x^2

Solution for 640=2x^2 equation:

640=2x^2

We move all terms to the left:

640-(2x^2)=0

a = -2; b = 0; c = +640;
Δ = b2-4ac
Δ = 02-4·(-2)·640
Δ = 5120
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:

$\sqrt{\Delta}=\sqrt{5120}=\sqrt{1024*5}=\sqrt{1024}*\sqrt{5}=32\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-32\sqrt{5}}{2*-2}=\frac{0-32\sqrt{5}}{-4}
=-\frac{32\sqrt{5}}{-4}
=-\frac{8\sqrt{5}}{-1}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+32\sqrt{5}}{2*-2}=\frac{0+32\sqrt{5}}{-4}
=\frac{32\sqrt{5}}{-4}
=\frac{8\sqrt{5}}{-1}
$