S
sagacious


cho [TEX](x+\sqrt{y^2+1})(y+\sqrt{x^2+1})=1[/TEX] c/m
[TEX](x+\sqrt{x^2+1})(y+\sqrt{y^2+1})=1[/TEX] đè thi HSG đó nhen
[TEX](x+\sqrt{x^2+1})(y+\sqrt{y^2+1})=1[/TEX] đè thi HSG đó nhen
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