Somebody help me please

Find the value of x for which abcd must be a parallelogram -9-6x x-30

Which shows one way to determine the factors of 4x3 + x2 – 8x – 2 by grouping?

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