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[Juliel]

Giải bất phương trình 

$$\frac{3}{\sqrt{3x+1}+2}\geq 2x+1$$

Edited by Juliel, 17-01-2014 - 20:47.

[Hoang Tung 126]

PT $< = > 3\geq (2x+1)\sqrt{3x+1}+4x+2< = > 1-4x\geq (2x+1)\sqrt{3x+1}< = > (1-4x)^2\geq (3x+1)(2x+1)^2$