4. A rectangular box without a lid is to be made from \( 12\mathrm{m}^2 \) of cardboard. Please use the method of Lagrange multiplier to find the maximum volume of such a box.(10%)
4. A rectangular box without a lid is to be made from \( 12\mathrm{m}^2 \) of cardboard. Please use the method of Lagrange multiplier to find the maximum volume of such a box.(10%)