L
lisjixthuylinh


cho a,b,c>0,abc=1.cmr
[tex]\frac{1}{a^2-a+1}[/tex]+[tex]\frac{1}{b^2-b+1}[/tex]+[tex]\frac{1}{c^2-c+1}[/tex]<=3
[tex]\frac{1}{a^2-a+1}[/tex]+[tex]\frac{1}{b^2-b+1}[/tex]+[tex]\frac{1}{c^2-c+1}[/tex]<=3
Last edited by a moderator: