Answers

2016-04-06T01:08:42+08:00
Insert  three geometric means between      1  &   256
   the first term is   1,    the fifth term is  256
      256 =   a r^n-1          / n = 5
       256       =   1 r^4
            r =   4
           so the sequence is           1, 4,16, 64, 256
            the third geometric mean is    64
6 4 6