计算,（a²-1）/（a²+4a+4）÷（a+1）/（a+2）
问题描述：
计算,
（a²-1）/（a²+4a+4）÷（a+1）/（a+2）
答
原式=（a+1）（a-1）/（a+2）² ×（a+2）/（a+1）
=[（a+1）（a-1）（a+2）]/[（a+2）²（a+1）]
=（a-1）/（a+2）
答
[（a²-1）/（a²+4a+4）]÷[（a+1）/（a+2）]
=[(a²-1)/(a+1)]/[(a²+4a+4)/(a+2)]
=(a-1)/(a+2)