Does anyone know the verbal expression for numbers 1, 2, 3, and 4?Please help me I’m sleep deprived

Which graph represents the parent function of y=(x+2)(x-2)

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

Consider the sequence below. 3 , 1 , 1/3 , 1/9 , select the explicit function which defines the sequence.