240-n2-n=0

Solution for 240-n2-n=0 equation:

240-n2-n=0

We add all the numbers together, and all the variables

-1n^2-1n+240=0

a = -1; b = -1; c = +240;
Δ = b2-4ac
Δ = -12-4·(-1)·240
Δ = 961
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{961}=31$
$n_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-31}{2*-1}=\frac{-30}{-2}
=+15
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+31}{2*-1}=\frac{32}{-2}
=-16
$