Question

An experiment is done to determine the number of bacteria on a piece of bread over time. The graph represents the function that models the data from the experiment, where y represents the number of bacteria, in thousands, given the number of days, x, since the experiment began.

Answer 1

First option

Explanation:

although it is true that the domain of an exponential function is all numbers, here we are talking about bacteria over time, time cannot be negative, so, the answer will be all numbers greater or equal to 0.

Answer 2

Recall that the domain of an exponential function is all real numbers, therefore the domain of the given function is all real numbers.

Answer: Last option.