Final answer:
In identifying exponential decay functions, we look for a form that has a negative exponent in the term with the base e. Amongst the options given, only the third function f(x) = -7e^x + 8 represents exponential decay because it has a negative base multiplier indicating a decreasing rate of change. Therefore, the only function that represents an exponential decay is option III. The correct answer is B) I and III only.
Step-by-step explanation:
The question asks to identify which functions represent exponential decay. An exponential decay function is of the form f(x) = a · e(-kx), where a is a positive constant, e is the base of natural logarithms, and k is a positive constant that represents the decay rate. For a function to represent exponential decay, its rate of change must decrease as x increases, which typically involves a negative exponent in the term with the base e.
Looking at the given functions:
- f(x) = 3.5 does not have the form of an exponential function.
- f(x) = 4 is also not an exponential function because it is a constant function.
- f(x) = -7ex + 8 is an example of exponential decay because the term -7ex indicates a decay with a negative base multiplier in front of the e term.
Therefore, the only function that represents an exponential decay is option III. The correct answer is B) I and III only.