find c what is the unit price at that level of demand
The demand function for the Luminar desk lamp is given by the following function where x is the quantity demanded in thousands and p is the unit price in dollars.
f'(x) = -.2x-.7
(b)What is the rate of change of the unit price when the quantity demanded is 4000 units (x = 4)?
$-1.5per 1000 lamps
(c)What is the unit price at that level of demand?