Question

An investment of $2000 in a bank account doubles every five years. The function that models the growth of this investment is f(x)=2000•2^x, where x is the number of doubling periods, or 10 years?

Answer 1

4150

Explanation:

Answer 2

x=1 after the first 5 years;
x=2 after the another 5 years (or better said after the first 10 years in the bank);
x=3 after another 5 years ( or better said after the first 15 years in the bank)
and so on...

x is the number of 5 years intervals which have passed up to a moment in time :)