Which expression is equivalent to (3x^2-6) – (5x^2-7x+5)-(9x+3)? A.-2x2–2x-4 B.-2x2–2x-14 C.-2x2-16x +2 D.-2x2–16x-14

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