Sarah needs a PVC pipe with a diameter of 10 inches and a height of 2 inches, how much material is needed to make 5 pipes?

At which value in the domain does f(x) =0?

On a piece of paper graph f(x)=5•(0.4)^x

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters