The letters of the word STAR are written on individual cards. If you always choose three cards and then put them back before the next set of three cards, how many different permutations will you have? List all the different permutations.

Select the lengths in centimeters that would form a right triangle

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

What are the solutions of the following system? y=-2x^2 y=x-2