What is the correct C++ function to calculate x = (b + sqrt(b³ - 1))/n?
a) x = (b + sqrt(b³ - 1))/n
b) x = (b - sqrt(b³ - 1))/n
c) x = (b + sqrt(b³ + 1))/n
d) x = (b - sqrt(b³ + 1))/n