5n^2+5n-800=0

Solution for 5n^2+5n-800=0 equation:

5n^2+5n-800=0

a = 5; b = 5; c = -800;
Δ = b2-4ac
Δ = 52-4·5·(-800)
Δ = 16025
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:

$\sqrt{\Delta}=\sqrt{16025}=\sqrt{25*641}=\sqrt{25}*\sqrt{641}=5\sqrt{641}$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-5\sqrt{641}}{2*5}=\frac{-5-5\sqrt{641}}{10}
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+5\sqrt{641}}{2*5}=\frac{-5+5\sqrt{641}}{10}
$