Question

find the surface area and volume of a rectangular prism with dimensions x, 3x+4, 3x+6

Answer 1

Let x be the height, 3*x+4 the width and 3*x+6 the length.

Surface area = twice the sum of the height, width and length.
\[2x(4+3x)+2x(6+3x)+2(4+3x)(6+3x)\text{=}48+80x+30x^2\]
Volumn is the product of the height, width and length.
\[x (4+3 x) (6+3 x)\text{==}24 x+30 x^2+9 x^3 \]

Answer 2

Surface area above is incorrect. It should have been:
\[2(x+(3x+4)+(3x+6))\text{==}14 x+20 \]