Question 22817
You do combine the terms.  Just be careful about the signs.  If the + in the middle had been a - it would have turned out quite different.
you try the question again, but this is what I got.  However, I do not know how your teacher likes these to be reduced.

there is no other^4 so there is nothing to add to that one
you have 2 ^3 so add these two numbers together
you have one x so there is nothing to add to that one
you have 2 numbers so add them together

I got

2x^4+8x^3-2x+9