Explanation
Correct answer: C.
Choice C is correct. It's given that represents the number of years since the account was opened. Therefore, represents the number of -year periods since the account was opened. Since the value of the account doubles during each of these -year periods, the value of the account can be found by multiplying the initial value by factors of . This is equivalent to . It's given that the initial value of the account is $. Therefore, the value of the account , in dollars, years after the account was opened can be represented by .
Desmos solution:
Enter in Desmos:
Reviewed and rewritten by CookSAT
Why the other choices are wrong
Choice A
Choice A is incorrect. This equation represents the value of an account if the value of the account halves, not doubles, every years.
Choice B
Choice B is incorrect. This equation represents the value of an account if the value of the account decreases by , not doubles, every , not , years.
Choice D
Choice D is incorrect. This equation represents the value of an account if the value of the account increases by a factor of , not doubles, every , not , years.