10n^2+9n-40=0

Solution for 10n^2+9n-40=0 equation:

10n^2+9n-40=0

a = 10; b = 9; c = -40;
Δ = b2-4ac
Δ = 92-4·10·(-40)
Δ = 1681
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1681}=41$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(9)-41}{2*10}=\frac{-50}{20}
=-2+1/2
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+41}{2*10}=\frac{32}{20}
=1+3/5
$