y^2+2y-9+3y-2
=y^2+2y+3y-9-2
=y^2+5y-11
Remember that the parenthesis that are located in your expression are meant to just group the two different factors since the operation is merely addition.... It would be different if cases like irrational factors such as (1/8ab^2) / (1/4ac^4) appeare....
