720=n(n^-1)

Solution for 720=n(n^-1) equation:

720=n(n^-1)

We move all terms to the left:

720-(n(n^-1))=0


We calculate terms in parentheses: -(n(n^-1)), so:

n(n^-1)

We multiply parentheses

n^2-1n

Back to the equation:

-(n^2-1n)


We get rid of parentheses

-n^2+1n+720=0

We add all the numbers together, and all the variables

-1n^2+n+720=0

a = -1; b = 1; c = +720;
Δ = b2-4ac
Δ = 12-4·(-1)·720
Δ = 2881
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{-(1)-\sqrt{2881}}{2*-1}=\frac{-1-\sqrt{2881}}{-2}
$
$n_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+\sqrt{2881}}{2*-1}=\frac{-1+\sqrt{2881}}{-2}
$