n^2-4n-20=4

Solution for n^2-4n-20=4 equation:

n^2-4n-20=4

We move all terms to the left:

n^2-4n-20-(4)=0

We add all the numbers together, and all the variables

n^2-4n-24=0

a = 1; b = -4; c = -24;
Δ = b2-4ac
Δ = -42-4·1·(-24)
Δ = 112
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{112}=\sqrt{16*7}=\sqrt{16}*\sqrt{7}=4\sqrt{7}$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-4)-4\sqrt{7}}{2*1}=\frac{4-4\sqrt{7}}{2}
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-4)+4\sqrt{7}}{2*1}=\frac{4+4\sqrt{7}}{2}
$