Add (3+2y−5y2+6y3), (−8+3y+7y3) and (5−6y−8y3+y2).
−y−4y2+5y3
To add : (3+2y−5y2+6y3), (−8+3y+7y3) and (5−6y−8y3+y2)
(−8+3y+7y3) does not have the term with y2. So, we add 0y2 and hence, the expression will be (−8+3y+0y2+7y3).
On adding there expressions, we get,
3+2y−5y2+6y3
−8+3y+0y2+7y3
5−6y+y2 −8y3––––––––––––––––––––––
−1y−4y2+5y3
(3+2y−5y2+6y3)+(−8+3y+7y3)+(5−6y−8y3+y2)=(−y−4y2+5y3)