Surface area cube2 = 2*(a^2 + 2a*a + 2a*a) = 10*a^2
can you tell me how you arrived at this ?
If each side of the original cube is a, then for the new cube the sides will be 2a, a, a.
Four faces of the new cube will have an area 2a*a and the remaining two faces have area a*a.
Surface area of a cuboid (rectangular solid) = 2(lb + lh + bh), where l,b,h are respectively the length, breadth and height of the solid.