M = (N-2)/N
M = N² - 2N
N² - 2N - M = 0
To find N we need to use quadratic formula.
For our equation x = N, a=1, b= -2, c= -M
[tex]x=\frac{-b+/-\sqrt{b^{2}-4ac} }{2a} \\ \\N=\frac{-(-2)+/-\sqrt{(-2)^{2} -4*1*(-M)} }{2*1} \\ \\ N=\frac{2+/-\sqrt{4+4M} }{2} \\ \\ N=\frac{-2+/-2\sqrt{1+M} }{2} = -1+/-\sqrt{1+M} \\ \\ N = -1 +\sqrt{1+M} \ or\ N=-1-\sqrt{1+M}[/tex]
