Question

A manufacturer's revuenve in dollars is given by R(x)=1500x-0.02x^2 where x is number of units sold.
Find the marginal revenue function. Use the derivative to estimate the revenue gained from selling the 35th unit.

The marginal revenue function is the derivative, dR/dx = 1500 - 0.04 x.
Insert x = 35 for the revenue gain by selling the 35th unit. It is still pretty close to $1500.