4*n^2-8*n-320=0

Solution for 4*n^2-8*n-320=0 equation:

4n^2-8n-320=0

a = 4; b = -8; c = -320;
Δ = b2-4ac
Δ = -82-4·4·(-320)
Δ = 5184
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5184}=72$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-72}{2*4}=\frac{-64}{8}
=-8
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+72}{2*4}=\frac{80}{8}
=10
$