不等式f(x)?1?0化为?x?2?1?0,解得x??1; 当
1?x?3时,f(x)?2x?1?(x?3)?3x?4, 2不等式f(x)?1?0化为3x?4?1?0,解得x?1,取1?x?3; 当x…3时,f(x)?2x?1?(x?3)?x?2,
不等式f(x)?1?0化为x?2?1?0,解得x??3,取x…3; 综上所述,不等式f(x)?1?0的解集为{x|x??1或x?1}; (2)当a?0吋,若x??a,则f(x)??2x?a?(x?3)??x?a?3, 2aa5此时f(x)min?f(?)???3,则f(x)?3a…a?3?2,解得a?1;
222a若??x?3,则f(x)?2x?a?(x?3)?3x?a?3,
2a15此时f(x)?f(?)??a?3,则f(x)?3a?a?3?2,解得a?1;
2223,则f(x)?2x?a?(x?3)?x?a?3, 若x…此时f(x)min?f(3)?6?a,则f(x)?3a…4a?6?2恒成立;
综上所述,不等式f(x)?3a?2对任意x?R恒成立时,a的取值范围是a?1.
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