36n2+28n-4000=0

Solution for 36n2+28n-4000=0 equation:

36n^2+28n-4000=0

a = 36; b = 28; c = -4000;
Δ = b2-4ac
Δ = 282-4·36·(-4000)
Δ = 576784
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:

$\sqrt{\Delta}=\sqrt{576784}=\sqrt{16*36049}=\sqrt{16}*\sqrt{36049}=4\sqrt{36049}$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-4\sqrt{36049}}{2*36}=\frac{-28-4\sqrt{36049}}{72}
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+4\sqrt{36049}}{2*36}=\frac{-28+4\sqrt{36049}}{72}
$