An open rectangular box with volume 2 m^3 has 6

An open rectangular box with volume 2m^{3} has a square base. Express the surface area of the box as a function of the length of a side of the base.


Let “x” represent the length of the box and “h” represent the height of the box. We know that the volume of the box is 2m^{3}, therefore,





The surface area of the box is, S=x^{2}+4xh. If we write the surface areas a function of “x” then



S(x)=x^{2}+(\frac{8}{x}) and the domain is x>0.

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6 thoughts on “An open rectangular box with volume 2 m^3 has

    • questionsolutions Post author

      Hi! So this is an open rectangular box with a square base. So if you draw it out, you will see that the bottom side is simply “x*x” (square base, which means each side is equal in length) which gives you surface area of the bottom side. Then we have 4 sides only, since the top is open. Each of the 4 sides is h*x (height x length). Since we have 4 of them, we get 4xh. So if we add everything to get the total surface area, we get, x^2+4xh.

      Hopefully that clears it up, if it didn’t, let us know, and we will draw a diagram to explain it even better. Many thanks and best of luck with your studies! 🙂

        • questionsolutions Post author

          Of course. Please refer to this diagram:

          As you can see on the diagram, there is a square base, and there is no top. The height of the rectangle is “h” and the length is “x”. Because it has a square base, the surface area for that side is x*x. Now, we consider the other 4 panels, labeled 1 to 4. Each of those has a surface area of x*h. There are 4 of them. So we get, 4xh. Hopefully, that helps clear it up. Let us know if you still need more clarification.

          Best of luck with your studies 🙂