28n^2-136n-20=0

Solution for 28n^2-136n-20=0 equation:

28n^2-136n-20=0

a = 28; b = -136; c = -20;
Δ = b2-4ac
Δ = -1362-4·28·(-20)
Δ = 20736
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{20736}=144$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-136)-144}{2*28}=\frac{-8}{56}
=-1/7
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-136)+144}{2*28}=\frac{280}{56}
=5
$