The population of a certain town was 17,000 at the start of the year
2000. Each year, people moving into town increase the population by 7%,
while people moving out of town decrease the population by 3%. In
addition, births increase the population by 5% each year.
write in recursive expression f(n) that shows the population at the beginning of the year as n, as a function of its population the proceeding year n-1