Qué valor tendrá la incógnita “x” en esta ecuación: 3x - 18 = 30?

Is this a polynomial function? i need to know asap

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

Graph the equationy=x^2 -[tex]y = x^{2} - 2[/tex]