The square iron sheet with side length of 48 cm is used to make an iron box without cover

The square iron sheet with side length of 48 cm is used to make an iron box without cover

Let the side length of the truncated small square be a and the volume of the iron box be v
V=(48-2a)^2×a=4a^3-192a^2+2304a (0

Set up equations to solve application problems: a rectangular piece of iron is 25cm in length and 15cm in width. Now cut out a small square with equal side length from its four corners, and fold up the four sides to make a rectangular box with 231 square centimeters in floor area. Find out the side length of each small square to be cut out?

231=3*7*11=21*11=(25-4)*(15-4)
So the side length of the cut small square is 4cm