Answer
6$a^{2}$+24a+24
Work Step by Step
Formula of surface area of a cube: 6$a^{2}$
Plug in value for $a$: 6$(x+2)^{2}$
Thus;
=6(x+2)(x+2)
=6[$x^{2}$+2x+2x+(2)(2)] (FOIL: First Outer Inner Last)
=6($x^{2}$+4x+4) (Simplify and combine like terms)
=6$x^{2}$+24x+24 (Distribute common factors to terms in parenthesis)
