math
posted by Sami on .
you want to make an opentopped box from a 20 cm by 20 cm piece of cardboard by cutting out equal squares from the corners and folding up the flaps to make the sides. what are the dimensions of each square, to the nearest hundredth of a cm, so that the volume of the resulting box will be more than 100 cubic centimeters.

Let x be the width of the square corners that are removed. The base of the box will have area
(20  2x)^2 = 400 80x + 4x^2
and the height of the sides will be x.
The volume is
V = x (4x^2  80x + 400)
Pick the value of x that gives you the volume they want. There is a very wide range of x values, from less than 1 inch to more than 9 inches, that result in a volume of more than 100 cm^3. Are you sure you copied the problem correctly? 
thankx alot for the answer, but i got the same equation and can not factor it.