Question

You need to build a box from an 8 inchby 10 inch piece of cardboard. To do this, you cut out squares of length x from the four corners of the box in order to fold the sides up. Verify that the volume of the box is given by the equation:

V= 4x^3â36x^2+ 80x

Answer 1

Explanation:

From the attached image below, let assume we have a square of diameter x by x which is to be cut from each corner of the cardboard sheet.

Thus, from the diagram

the length = 8 - 2x the width = 10 - 2x and the height = x

So, the volume V = L*w*h

Volume (V) = (8 - 2x) (10 - 2x) x

V = (80 - 16x - 20x +4x²)x

V = 80x -36x² + 4x³

By rearrangement:

V = 4x³ - 36x² + 80x