show that if r is a primitive root modulo the positive integer m then the r^-1 is also a primitive root modulo m, where r^-1 is an inverse of r modulo m
Hello,
A precision (just in case) :
$\displaystyle \phi(m)$ stands for the Euler Totient function. It also designs the cardinal of the subgroup containing the invertible elements taken from Z/mZ.
This is why $\displaystyle a^{\phi(m)}$ is always $\displaystyle \equiv 1 [m]$.