The total worldwide box-office receipts for a long-running movie are approximated by the following function where T(x) is measured in millions of dollars and x is the number of years since the movie's release.
T(x) = (120x^2)/(x^2 + 4)
How fast are the total receipts changing 1 yr, 4 yr, and 8 yr after its release? (Round your answers to two decimal places.)
after 1 yr $ million/year
after 4 yr $ million/year
after 8 yr $ million/year