Find the point(s) on the graph of f where the tangent line is horizontal. (If an answer does not exist, enter DNE.) f(x) = smaller x-value larger x-value Need Help? X x +9 (x, y) = (x, y) = Read It Master It 18. [-/3 Points] DETAILS 120x T(x) = x + 4 TANAPCALCBR10 3.2.060. How fast are the total receipts changing 1 yr, 4 yr, and 6 yr after its release? (Round your answers to two decimal places.) after 1 yr $ after 4 yr $ after 6 yr $ Need Help? Box-Office Receipts The total worldwide box-office receipts for a long-running movie are approximated by the following function where 7(x) is measured in millions of dollars and x is the number of years since the movie's release. Read It million/year million/year million/year MY NOTES Watch It ASK YOUR TEACHER PRAC