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A box without a top is to be made by cutting equal squares from the corners of a rectangular piece of tin [math]30[/math] inches by [math]48[/math] inches and bending up the sides. What size should the squares be is the volume of the box is to be a maximum? [ph Hint: If [math]x[/math] is the side of a square, [math]V(x) = x(30-2x)(48-2x)[/math].]