2n^2-5n=9

Solution for 2n^2-5n=9 equation:

2n^2-5n=9

We move all terms to the left:

2n^2-5n-(9)=0

a = 2; b = -5; c = -9;
Δ = b2-4ac
Δ = -52-4·2·(-9)
Δ = 97
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-5)-\sqrt{97}}{2*2}=\frac{5-\sqrt{97}}{4}
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-5)+\sqrt{97}}{2*2}=\frac{5+\sqrt{97}}{4}
$