Ta có :
xy . yz . zx = `2/3` . `3/5` . `2/5` = `4/25`
⇒`(xyz)^2` = `4/25`
⇒\(\left[ \begin{array}{l}xyz=2/5\\xyz=-2/5\end{array} \right.\)
Với xyz=`2/5`
⇒z = `2/5` : `2/3` = `3/5`
⇒x = `2/5` : `3/5` = `2/3`
⇒y = `2/5` : `2/5` = 1
Với xyz = `-2/5`
⇒z = `-2/5` : `2/3` = `-3/5`
⇒x = `-2/5` : `3/5` = `-2/3`
⇒y = `-2/5` : `2/5` = -1