`x^(2).3^2=9`
`⇔x^(2).9=9`
`⇔x^2=1`
`⇔x=±1`
`x^2y^2=9`
`⇔|xy|=3`
⇔\(\left[ \begin{array}{l}xy=3\\xy=-3\end{array} \right.\)
`+)x=-1`
`⇒`\(\left[ \begin{array}{l}-y=3\\-y=-3\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}y=-3\\y=3\end{array} \right.\)
`+)x=1`
`⇒`\(\left[ \begin{array}{l}y=3\\y=-3\end{array} \right.\)
Vậy x=-1⇒\(\left[ \begin{array}{l}y=-3\\y=3\end{array} \right.\)
x=1⇒\(\left[ \begin{array}{l}y=3\\y=-3\end{array} \right.\)
