Question 1153933
I am assuming that length refers to the length of one edge of the cube (all edges of a cube are equal).
The area of the base (which is a square) is nothing but the length multiplied by breadth (which is also equal to the length)

So the expression for area of the base is
{{{(3x+2)*(3x+2) = 9x^2+12x+4}}}