问题 填空题 (1)9mn236n3=m() (2)x2+2xy+y2x2-y2=x+y(). 答案 (1)9mn236n3=m4n;(2)x2+2xy+y2x2-y2=(x+y)2(x+y)(x-y)=x+yx-y.故答案为:4n,x-y.