There are boxes without tops. Find the box with the least surface area for a given volume, V. Make a diagram (if you can).
Hint: Volume=x^2y
Area=x^2+4xy
so, area = x^2 + 4x(v/x^2) = x^2 + 4v/x
Now just find when that is a minimum
Hint: Volume=x^2y
Area=x^2+4xy
Now just find when that is a minimum