OG详解-OG3 数学1 Q2

Choice C is correct. The value of f(2) is the value of f(x) when x = 2.Substituting 2  for x  in the given function yields  f(2)= (2)³ +15, or f (2)= 8 +15, which is equivalent to  f(2)= 23. Therefore, the value of f(2) is 23.
Choice A is incorrect and may result from conceptual or calculation errors.  Choice B is incorrect. This is the value of f(2) when f(x)= x (3)+15, rather  than f(x)= x³ +15. Choice D is incorrect and may result from conceptual or calculation errors.