Originally Posted by

**Joel** I was asked this question in an exam, Could you please check my working and see if I was on the right track.

A square sheet of cardboard is 16cm on each side. Squares of side 'x' cm are cut from each corner and the sodes bent up to form an open box. What is the maximum volume of the box?

My working

Volume = L x B x H

= (16-2x)(16-2x)(x)

= x(16-2x)²

= x(256 - 64x + 4x²)

= 4x³ - 64x² + 256x *

to find maximum find v'=0

12x² -128x + 256 = 0

4(3x² -32x + 64) = 0

Need help from here