91Ó°ÊÓ

Find primitive roots of the following integers (if there are none, say so): \(6,10,12\), \(14,15 .\)

Solve each of the following systems of simultaneous linear congruences; if there is no solution, write "none." \((a) x \equiv 2(\bmod 3) ; x \equiv 3(\bmod 4) ; x \equiv 1(\bmod 5) ; x \equiv 4(\bmod 7)\) \((b) 6 x \equiv 4(\bmod 8) ; 10 x \equiv 4(\bmod 12) ; 3 x \equiv 8(\bmod 10)\) (c) \(5 x \equiv 3(\bmod 6) ; 4 x \equiv 2(\bmod 6) ; 6 x \equiv 6(\bmod 8)\)