The function y = 45x + 6 can be used to determine the cost for a person to purchase x tickets to a concert. A person can purchase up to 8 tickets. What is an appropriate domain for the function?
all integers < 8
all positive integers < 8
all positive real numbers < 8
the answer is all positive integers < 8
because the number of tickets can not be a negative number and must be a positive integer less than 8