题目内容
若不等式2x-1>m(x2-1)对满足|m|≤2的所有m都成立,求x的取值范围.
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方法一 原不等式化为(x2-1)m-(2x-1)<0.
令f(m)=(x2-1)m-(2x-1)(-2≤m≤2).
则
解得
<x<
.
方法二 求已知不等式视为关于m的不等式,
(1)若x2-1=0,即x=±1时,不等式变为2x-1>0,即x>
,∴x=1,此时原不等式恒成立.
(2)当x2-1>0时,使
>m对一切|m|≤2恒成立的充要条件是
>2,
∴1<x<
.
(3)当x2-1<0时,使
<m对一切|m|≤2恒成立的充要条件是
<-2.
∴
<x<1.
由(1)(2)(3)知原不等式的解集为
.
令f(m)=(x2-1)m-(2x-1)(-2≤m≤2).
则

解得


方法二 求已知不等式视为关于m的不等式,
(1)若x2-1=0,即x=±1时,不等式变为2x-1>0,即x>

(2)当x2-1>0时,使


∴1<x<
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(3)当x2-1<0时,使
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
∴

由(1)(2)(3)知原不等式的解集为

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