=12/(m+3)(m-3)-2/(m-3)+1/(m+3)
=12/(m+3)(m-3)-2(m+3)/(m+3)(m-3)+(m-3)/(m+3)(m-3)
=(12-2m-6+m-3)/(m+3)(m-3)
=(-m+3)/(m+3)(m-3)
=-1/(m+3)问一下，y—x分之x的平方—y的平方能化简吗？化简后为多少=(x+y)(x-y)/[-(x-y)]=-(x+y)=-x-y 请采纳