Question

Which is equivalent to 4/9 1/2^x

Answer 1

You have not provided a list of possible equivalents to (4/9)(1/2)^x.  But you can still try to simplify (4/9)(1/2)^x.

Start with (1/2)^x.  This is the same as         1^x
                                                                     -------
                                                                       2^x

Now multiply both sides by (4/9):

                         4(1)
(4/9)(1/2)^x =  ---------
                          2^x

or         4
         --------
           2^x

You could also write this as 

   2 (2)            2^1
----------  = 2 --------  = 2*2^(1-x)    or 2[2^(1-x)]
   2^x             2^x

Answer 2

Answer: It's B

9^1/8x