a²+2a-8=0(a+4)(a-2)=0a1=-4a2=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=(...