Finding the total surface area of cuboid model using volume

You are to design a cuboid model with a square base that has a volume of $12{m}^{3}$. In order to have a minimum total surface area for the cuboid, what are the values for the height of the cuboid and the length of a side in the square base?

So far, this is what I have done:

$\text{Volume =}L.B.H={B}^{2}.H$

$12={B}^{2}.H$

$H=\frac{12}{{B}^{2}}$

$\text{S.A. =}2.{B}^{2}+4.B.H$

$=2.{B}^{2}+4.B.(\frac{12}{{B}^{2}})$

$=2.{B}^{2}+\frac{48}{B}$

You are to design a cuboid model with a square base that has a volume of $12{m}^{3}$. In order to have a minimum total surface area for the cuboid, what are the values for the height of the cuboid and the length of a side in the square base?

So far, this is what I have done:

$\text{Volume =}L.B.H={B}^{2}.H$

$12={B}^{2}.H$

$H=\frac{12}{{B}^{2}}$

$\text{S.A. =}2.{B}^{2}+4.B.H$

$=2.{B}^{2}+4.B.(\frac{12}{{B}^{2}})$

$=2.{B}^{2}+\frac{48}{B}$