定义域:(a²-1)x²+(a-1)x+2/(a+1)≥0,且a+1≠0
①a²-1=0,即a=1时,2/(1+1)=1≥0,恒成立
②a²-1>0,即a>1或a<-1时,
△=(a-1)²-4(a²-1)×2/(a+1)≤0
得a²-10a+9≤0
(a-1)(a-9)≤0
解得1<a≤9
综上:1≤a≤9
答案:1≤a≤9
定义域:(a²-1)x²+(a-1)x+2/(a+1)≥0,且a+1≠0
①a²-1=0,即a=1时,2/(1+1)=1≥0,恒成立
②a²-1>0,即a>1或a<-1时,
△=(a-1)²-4(a²-1)×2/(a+1)≤0
得a²-10a+9≤0
(a-1)(a-9)≤0
解得1<a≤9
综上:1≤a≤9
答案:1≤a≤9