

Cho [tex] x,y,z>0 , x+y+z=xyz[/tex]
[tex]\frac{1}{\sqrt{1+x^{2}}}+\frac{1}{\sqrt{1+y^{2}}}+\frac{1}{\sqrt{1+z^{2}}}\leqslant \frac{3}{2}[/tex]
[tex]\frac{1}{\sqrt{1+x^{2}}}+\frac{1}{\sqrt{1+y^{2}}}+\frac{1}{\sqrt{1+z^{2}}}\leqslant \frac{3}{2}[/tex]