and  find: 

(f+g)(x) 

That just means to add together everything written after "f(x)=" and
everything written after "g(x)".

In other words it means the green stuff below PLUS the red stuff below:

 

So put a plus sign between the red and the green stuff:



Now you have to simplify.  I'll recolor the terms:



Now 

1. Write down the  because that's the only
term that has , and also because it has the largest exponent

2. After that combine the red things . That gives
 and you can just write that .

3. Finally combine the green things , getting -1 and you end up with:



Didn't take a rocket scientist, did it.  Bet you remember that much
from algebra five years ago.  :-)

Edwin