10. Find the volume

A square metal sheet has the length, \(a =\) 36 \(cm\). It is turned into a tray by cutting and turning equal corner squares of the metal sheet. Express the volume of the tray in the function of \(x\).

 

 

The volume of the square tray \(=\) $ix-i{x}^2-i{x}^3$ \(cm^3\)