一條o數 想試下自己數學身手就來挑戰吧 !開方(n+開方(n+開n........

sqrt[n + sqrt( n + sqrt (n+........... = x. where sqrt means square root.
That is
sqrt( n + x ) = x
n + x = x^2
x^2 - x - n = 0
By quadratic formula,
x = [1 +/- sqrt(1 + 4n)]/2.