Ta có xy=a,yz=b,zx=c =>x^2.y^2.z^2=abc/. x^2.y^2=a^2./ y^2 . z^2=b^2 /x^2.z^2=c^2/Vậy x^2.b^2=abc/a^2.z^2=abc/y^2.c^2=abc/x^2=[tex]\frac{ac}{b};y^2=\frac{ab}{c};z^2=\frac{bc}{a}[/tex]. Vậy x^2+y^2+z^2=[tex]\frac{ac}{b}+\frac{ab}{c}+\frac{bc}{a}=\frac{a^2.b^2b^2.c^2}{abc}[/tex]
nếu hay like cho mik nhé