What is f(x) ?
If f(x) = x + x + .. (x times).. + x, then answer would be --

(1) No
(2) No

Explanation :
(1) For all x, f'(x) would not be some constant like 5, or 10.
It would be 2x.
(2) For x = 5, f'(x) would be 2*5 = 10.

(Very basic differentiation question.)