\(\Leftrightarrow\left\{{}\begin{matrix}x^2+3y=1\\9x^2-3y=3\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x^2+3y=1\\10x^2=4\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}y=\dfrac{1-x^2}{3}\\x^2=\dfrac{2}{5}\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}y=\dfrac{1}{5}\\x^2=\dfrac{2}{5}\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}y=\dfrac{1}{5}\\x=\pm\dfrac{\sqrt{10}}{5}\end{matrix}\right.\)
Đặt \(x^2=a\left(a\ge0\right)\)
\(\Leftrightarrow\left\{{}\begin{matrix}a+3y=1\\3a-y=1\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}3a+9y=3\\3a-y=1\end{matrix}\right.\\ \Leftrightarrow10y=2\Leftrightarrow y=\dfrac{1}{5}\\ \Rightarrow a=\dfrac{2}{5}\left(tm\right)\)
\(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{\sqrt{10}}{5}\\x=-\dfrac{\sqrt{10}}{5}\end{matrix}\right.\)
