communication channel: calculating number of stakeholders


For communication channel can any one help me out calculating number of stakeholders , if number of communication channels were provide in the question .

Suppose question says there are total 10 communication channels find the total number of stakeholders

The formula for total no. of communication channels T=n*(n-1)/2

Put the value of T=10 and solve the quadratic equation
It will be n^2 - n - 20 = 0
n^2 - 5n +4n -20 =0 (factorize 20 in such a way that you get a difference of 1)
n(n-5)+ 4(n-5) =0
either n=5 or n=-4, since the value cannot be in negative so the value of n=5