HOC24
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Môn học
Chủ đề / Chương
Bài học
a) \(\left\{{}\begin{matrix}\left|x\right|+4\left|y\right|=18\\3\left|x\right|+\left|y\right|=10\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}3\left|x\right|+12\left|y\right|=54\\3\left|x\right|+\left|y\right|=10\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}11\left|y\right|=44\\3\left|x\right|+\left|y\right|=10\end{matrix}\right.\)
<=> \(\left\{{}\begin{matrix}y=\pm4\\x=\pm2\end{matrix}\right.\)
Vậy ...
\(\Leftrightarrow\left\{{}\begin{matrix}2x^2+2y^2=26\\3x^2-2y^2=-6\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2x^2+2y^2+3x^2-2y^2=20\\x^2+y^2=13\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}5x^2=20\\x^2+y^2=13\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x^2=4\\y^2=9\end{matrix}\right.\Leftrightarrow}\left\{{}\begin{matrix}x=\pm2\\y=\pm3\end{matrix}\right.\)