已知实数a满足a²+2a-8=0,求（a+1）分之1-（a²-1）分之（a+3）÷（a-1）分之（a+1）的值
问题描述：
已知实数a满足a²+2a-8=0,求（a+1）分之1-（a²-1）分之（a+3）÷（a-1）分之（a+1）的值
答
a²+2a=8
原式=1/(a+1)-(a+3)/(a+1)(a-1)×(a-1)/(a+1)
=1/(a+1)-(a+3)/(a+1)²
=(a+1-a-3)//(a+1)²
=-2/(a+1)²
=-2/(a²+2a+1)
=-2/(8+1)
=-2/9
答
a²+2a-8=0(a+4)(a-2)=0a1=-4 a2=2（a+1）分之1-（a²-1）分之（a+3）÷（a-1）分之（a+1）=（a+1）分之1-（a²-1）分之（a+3）×（a+1）分之（a-1）=（a+1）分之1-（a+1）分之（a+3）×（a+1）分之1=(...