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1202.


1 )Cho a thuộc N* . CMR :
[TEX]\frac{a}{a+b} + \frac{ b }{b+c } + \frac{c }{a+c } > 1[/TEX]
2) CHO a ,b,c khác 0 ; a+b+c khác 0
thoả mãn [TEX]\frac{1}{a}+\frac{1}{b}+\frac{1}{c} = \frac{1}{a+b+c} [/TEX]
CMR :[TEX]\frac{1}{a ^ {2009}} +\frac{1}{b^{2009}} + \frac{1}{c^{2009}} = \frac{1}{a^{2009}+b^{2009}+c^{2009}}[/TEX]
~> CHú ý latex
[TEX]\frac{a}{a+b} + \frac{ b }{b+c } + \frac{c }{a+c } > 1[/TEX]
2) CHO a ,b,c khác 0 ; a+b+c khác 0
thoả mãn [TEX]\frac{1}{a}+\frac{1}{b}+\frac{1}{c} = \frac{1}{a+b+c} [/TEX]
CMR :[TEX]\frac{1}{a ^ {2009}} +\frac{1}{b^{2009}} + \frac{1}{c^{2009}} = \frac{1}{a^{2009}+b^{2009}+c^{2009}}[/TEX]
~> CHú ý latex
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