If the height of a rectangular prism is doubled then the surface area of the prism is and i need work to me

The surface area of a rectangular prism (S) is given in terms of length L, width W, and height H by
.. S = 2(LW +H(L +W))

If you double the height, now you have new surface area S'
.. S' = 2(LW +2H(L +W)) = 2(LW +H(L +W)) +2H(L +W)
.. = S +2H(L +W)

This is larger than the original surface area S, but is not as much as 2S.

Selection C is appropriate.

3x+9+4x+x=8x+9that's the answer for your question.