4x^2-8x-256=0

Solution for 4x^2-8x-256=0 equation:

4x^2-8x-256=0

a = 4; b = -8; c = -256;
Δ = b2-4ac
Δ = -82-4·4·(-256)
Δ = 4160
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:

$\sqrt{\Delta}=\sqrt{4160}=\sqrt{64*65}=\sqrt{64}*\sqrt{65}=8\sqrt{65}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-8\sqrt{65}}{2*4}=\frac{8-8\sqrt{65}}{8}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+8\sqrt{65}}{2*4}=\frac{8+8\sqrt{65}}{8}
$