7n^2-39n-18=0

Solution for 7n^2-39n-18=0 equation:

7n^2-39n-18=0

a = 7; b = -39; c = -18;
Δ = b2-4ac
Δ = -392-4·7·(-18)
Δ = 2025
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2025}=45$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-39)-45}{2*7}=\frac{-6}{14}
=-3/7
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-39)+45}{2*7}=\frac{84}{14}
=6
$