What should i do- this is hard

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

Which function has the domain x> -11? y= x+ 11 +5 y= x-11 +5 y= x+5 - 11 y= x+5 + 11

How do i simply this radical expression?