Please give me the correct answer. Only answer if you're very good at math. Please don't send a link to a website.​

Write the expression as a single natural logarithm. 2 in a - 4 in y

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

Factor and solve to find roots x squared -x - 90 =0