Question #d5da6

1 Answer
Feb 13, 2018

#SA=6x^2+36x+22#

Explanation:

The surface area of a rectangular prism is given by:

#2*(hw+hl+wl)# where

#h# is the height, #w# is the width, and #l# is the length.

#-----------------#

In this case, #h=(x-1), w=(x+7), l=(x+3)#.

Plug into the formula:

#2*((x-1)(x+7)+(x-1)(x+3)+(x+7)(x+3))#

#2*(x^2+6x-7+x^2+2x-3+x^2+10x+21)#

#2*(3x^2+18x+11)#

#6x^2+36x+22#

Yay!