Question 201242
In general functions are compressed horizontally by a factor of two when you replace the 'x' in the function with '2x'.

The solution for this particular problem would be:
  f(x) = 8 ^(2x)

This can be simplified...
  f(x) = 8 ^ (2 * x)
  f(x) = (8 ^ 2) ^ x
  f(x) = 64 ^ x