-2*(1+h)³

There is a number of ways that this can be done.

If you are a junior student then

I suggest that you multiply   (1+h)(1+h)

then mulpiply the answer by (1+h)

then multply that answer by -2

-2*(1+h)³=-2*(1+h)*(1+h)*(1+h)

               =-2*(1+h+h+h²)*(1+h)

               =-2*(1+2h+h²)*(1+h)

               =-2*(1+h+2h+2h²+h²+h³)

               =-2*(1+3h+3h²+h³)

               =-2-6h-6h²-2h³