The price-demand equation and the cost function for the production of HDTVs are given, respectively, by
$x=9,000-30 p \quad$ and $\quad C(x)=150,000+30 x$
where $x$ is the number of HDTVs that can be sold at a price of $\$ p$ per $T V$ and $C(x)$ is the total cost (in dollars) of produc ing $x$ TVs.
(A) Express the price $p$ as a function of the demand $x$, and find the domain of this function.
(B) Find the marginal cost.
(C) Find the revenue function and state its domain.
(D) Find the marginal revenue.
(E) Find $R^{\prime}(3,000)$ and $R^{\prime}(6,000)$ and interpret these quantities.
(F) Graph the cost function and the revenue function on the same coordinate system for $0 \leq x \leq 9,000$. Find the break-even points and indicate regions of loss and profit.
(G) Find the profit function in terms of $x$.
(H) Find the marginal profit.
(I) Find $P^{\prime}(1,500)$ and $P^{\prime}(4,500)$ and interpret these quantities.