The formula y = fx/x - f models the relationships needed to focus an image where y is the distance between the film and projector lens, x is the distance between the move screen and the projector lens, and f is the focal length.

a) Sketch the graph of this rational function for f = 5 centimeters

b) Bob and Carol are showing home movies. Use the graph to describe the desired

distance between the film and the projector lens as Carol moves the projector further from

the screen.