Ta có :
\(xy=\dfrac{1}{3}\) ; \(yz=\dfrac{-2}{5}\)
\(\Leftrightarrow x.y.y.z=\dfrac{1}{3}.\left(\dfrac{-2}{5}\right)\)
\(\Leftrightarrow x.z.y^2=\dfrac{-2}{15}\)
Mà \(x.z=\dfrac{-3}{10}\)
\(\Leftrightarrow\dfrac{-3}{10}.y^2=\dfrac{-2}{15}\)
\(\Leftrightarrow y^2=\dfrac{4}{9}\)
\(\Leftrightarrow\left[{}\begin{matrix}y=\dfrac{2}{3}\\y=\dfrac{-2}{3}\end{matrix}\right.\)
Mà \(xy=\dfrac{1}{3}\)
+)Với \(y=\dfrac{2}{3}\Leftrightarrow x=\dfrac{1}{2}\)
+) Với \(y=\dfrac{-2}{3}\Leftrightarrow x=-\dfrac{1}{2}\)
Mà \(xz=\dfrac{-3}{10}\)
+) Với \(x=\dfrac{1}{2}\Leftrightarrow z=\dfrac{-3}{5}\)
+) Với \(x=-\dfrac{1}{2}\Leftrightarrow z=\dfrac{3}{5}\)
Vậy .....
