A cuboid tank is open at the top and the internal dimensions of its base are x m and2xm.

The height ishm.

The volume of the tank isVcubic metres and the volume is fixed. LetS mēdenote the internal surface area of the tank.

S in terms of x and h

S in terms of V and x

Sub

The maximal domain ofSin terms ofVandxis

If find the maximum value ofSif

I'm stuck here, can anyone please help?

Here's a visual representation of the cuboid