What is the result of isolating y2 in the equation below? 9x2 + 7y2 = 42

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

Twelve less than a number is at most 20

What is the graph of the absolute value equation ? y=|x|-5