Since the sequence is geometric, there is some constant 
such that the sequence is recursively given by
By this definition, you can recursively substitute into the right hand side the definition for
to find an explicit formula for the 
th term.
You know the second term, which means you can find:
So, the 7th term of the sequence is
By this definition, you can recursively substitute into the right hand side the definition for
You know the second term, which means you can find
So, the 7th term of the sequence is