-7n^2+23n+20=0

Solution for -7n^2+23n+20=0 equation:

-7n^2+23n+20=0

a = -7; b = 23; c = +20;
Δ = b2-4ac
Δ = 232-4·(-7)·20
Δ = 1089
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1089}=33$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(23)-33}{2*-7}=\frac{-56}{-14}
=+4
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(23)+33}{2*-7}=\frac{10}{-14}
=-5/7
$