Determine whether the mapping is a relation or a function or neither. the 4th awnser was cannot be determined

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

Asequence is a function whose is the set of natural numbers

Which statement is true about the local minimum of the graphed function? over the interval[-4,-2], the local minimum is 0. over the interval [-2,-1] , the local minimum is 25. over the interval [-1,4], the local minimum is 0. over the interval [4,7], the local minimum is -7