(m+1)x2 -mx+m-1=0有实数根时，m的取值范围是集合A如果m=-1 那么方程是x-2=0有实数根如果m≠-1 方程有实数根△=m²-4（m+1）（m-1）=m²-4m²+4=4-3m²>=0-2根号3/3<=m<=2根号3/3 且m不等于-1综上A={-2根号3/3<=m<=2根号3/3}B不完整，没法解
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