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$\begin{array}{l}
1)\,\,\,\,\left( {\sqrt {2,\,\,1} } \right)\\
2)\,\,\,\left( {2,\,4} \right)\,,\,\,\left( {\frac{1}{2}\,\,,\frac{1}{4}} \right)\\
3)\,\,\,\left( {4,\,32} \right)\,,\,\,\left( { - 1,\,1} \right)
\end{array}$
$4)\,\,$: $x,\,y,\,z\, > 0$
Hệ viết lại $\left\{ \begin{array}{l}
{\log _2}x\sqrt {yz} = 2\\
{\log _3}y\sqrt {xz} = 2\\
{\log _4}z\sqrt {xy} = 2
\end{array} \right.\,\,
\Leftrightarrow \,\,\,\,\,\,\left\{ \begin{array}{l}
{x^2}yz = 16\\
{y^2}xz = 81\\
{z^2}xy = 256
\end{array} \right.$
ĐS : $\left( {\frac{2}{3},\,\frac{{27}}{8},\,\frac{{32}}{3}}
\right)$
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