Giải các hpt sau :
\(1,\left\{{}\begin{matrix}x\sqrt{y}+y\sqrt{x}=30\\x\sqrt{x}+y\sqrt{y}=35\end{matrix}\right.\)
\(2,\left\{{}\begin{matrix}\left(x+y\right)\left(1+\dfrac{1}{xy}\right)=5\\\left(x^2+y^2\right)\left(1+\dfrac{1}{x^2y^2}\right)=9\end{matrix}\right.\)
\(3,\left\{{}\begin{matrix}x+y+\dfrac{1}{x}+\dfrac{1}{y}=5\\x^2+y^2+\dfrac{1}{x^2}+\dfrac{1}{y^2}=49\end{matrix}\right.\)