Let f a b and g : b -> c be maps.
(d) if g of is one-to-one and f is onto, show that g is one-to-one. (e) if go f is onto and g is one-to-one, show that f is onto.

Suppose that the price p (in dollars) and the weekly sales x (in thousands of units) of a certain commodity satisfy the demand equation 4p cubedplusx squaredequals38 comma 400. determine the rate at which sales are changing at a time when xequals80, pequals20, and the price is falling at the rate of $.20 per week.