30^(3m+1)=[30^(3m)]×30=[(2×5×3）^(3m)]×30= [2^(3m)]×[5^(3m)]×[3^(3m)]×30=(2^m)³×(5^m)³×(3^m)³×30=a³×b³×c³×30=30a³b³c³