1: 7. [-/4 Points] DETAILS TANAPCALC10 3.R.066. ASK Demand for Smartphones The marketing department of Telecon has determined that the demand for their smartphones obeys the relationship p = -0.02x + 900 (0 s x S 30,000) where p denotes the phone's unit price (In dollars) and x denotes the quantity demanded. (a) Find the revenue function R. R(X) = (b) Find the marginal revenue function R'. R'(X) = (c) Compute R'(7,000) (in dollars). $ Interpret your result. O The 7,001st phone will have a price equal to the above amount. The sale of the 7,001st phone will bring a revenue equal to the above amount. O The 7,000th phone will have a price equal to the above amount. The sale of the 7,000th phone will bring a revenue equal to the above amount