Jawabanmu

2014-08-09T16:55:28+07:00
2x²+6x+4y-1 - (-x +y)
2x² + 6x+x +4y-y -1
= 2x² + 7x +3y -1

semoga membantu :-) 
2x²+6x+4y-1
2x²+6x+4y-1+x-y
2x²+7x+3y-1