# FIND C! What is the unit price at that level of demand?

**Question description**

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.

p=f(x)= -0.1x^2-0.7x+33

(a)Find f’(x)

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?

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