If the relationships below are given in the for input, output, which pairing always describes a function?

Which of the following is true for the relation f(x)=2x^2+1

Match each function with its rate of growth or decay

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