the initial number of bacteria in a culture is 12,000. the xulture doubles each day write an exponential functin to model the population Y of bacteria after X days

The equation would be y=12000(2)ˣ.

This equation is of the form y=a*bˣ, where a is the initial population and b is the rate that it increases by.  In this problem, a = 12000 and b=2, since it doubles each time.