OG详解-OG5 数学1 Q24

Choice D is correct. A function of the form f(x) = a(b)^x + c, where a<0 and b> 1, is a decreasing function. Both of the given functions are of this form; therefore, both are decreasing functions. If a function f is decreasing, as the value of x increases, the corresponding value of f(x) decreases; therefore, the function doesn’t have a minimum value. Thus, neither of the given functions has a minimum value.
Choice A is incorrect and may result from conceptual or calculation errors. Choice B is incorrect and may result from conceptual or calculation errors. Choice C is incorrect and may result from conceptual or calculation errors.