当a为何值时,不等式(a^2-1)x^2-(a-1)x-1

问题描述:

当a为何值时,不等式(a^2-1)x^2-(a-1)x-1

要想不等式(a^2-1)x^2-(a-1)x-1①(a^2-1)x^2-(a-1)x-1开口要向下
即:a^2-1解得:-1②判别式△△=b^2-4ac=(a-1)^2+4(a^2-1)解得:-1/5取交集得:-1/5