Is that how the question was originally asked? There's no problem, but it seems strange. Were you told what the function, f(x), was? You see (-4,-4) is just a single point, not a function. So depending on the function, we cannot know what 1/2 f(x) will be.
e.g. if f(x) = -4(x), then f(x) when x =1 is -4
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