算了,一次提完吧,
11.分解因式：(1)（x+y)(x+y+2xy)+(xy+1)(xy-1)
(2)(x+y)(x+y+2xy)+(xy+1)(xy-1)
12.若a-b=2,a-c=1/2,求(b-c)^2-3(b-c)+9/4的值.
13.解方程：（x-2)(x+3)+(2-x)^2-(x-2)(2x-3)=20
14.算一算：1+2=?
求你们全部回答吧