Tìm x,y,x biết

N

noinhobinhyen

[TEX]\frac{x^2}{2}+ \frac{y^2}{3}+ \frac{z^2}{4}= \frac{x^2+y^2+z^2}{5}[/TEX]
[TEX]\Leftrightarrow \frac{6x^2+4y^2+3z^2}{12}= \frac{x^2+y^2+z^2}{5}[/TEX]
[TEX]\Leftrightarrow 30x^2+20y^2+15z^2=12x^2+12y^2+12z^2[/TEX]
[TEX]\Leftrightarrow 18x^2+8y^2+3z^2=0 \Leftrightarrow \fbox{x=y=z=0}[/TEX]
 
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