Answer:
The answer depends on what the problem really is.
f(1/2) = 8
or
f(1/2) = 4
See below.
Explanation:
This is the problem as it was posted:
y = f(x) = 16x
Let x = 1/2
y = f(1/2) = 16(1/2) = 8
Perhaps the problem is this:

If x is an exponent of 16 and not a factor, then the answer is:
