a-1/a+2÷a²-2a+1/a²-4×a+3/a²+a-6
问题描述：
a-1/a+2÷a²-2a+1/a²-4×a+3/a²+a-6
答
a-1/a+2÷a²-2a+1/a²-4×a+3/a²+a-6
=a-1/a+2÷（a-1）²/(a+2)(a-2)×(a+3)/(a-2)(a+3)
=(a-1)/(a+2)×(a+2)(a-2)/(a-1)² ×1/(a-2)
=(a-2)/(a-1) ×1/(a-2)
=1/(a-1)m²-n²/（m-n）² ×（n-m/mn)² ÷m+n/m
那么这道题的怎么做m²-n²/（m-n）² ×（n-m/mn)² ÷m+n/m
=（m+n）/(m-n)×(m-n)²/m²n²×m/(m+n)
=(m-n)/mn²