Question

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Answer 1

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Answer 2

\(\Leftrightarrow\left\{{}\begin{matrix}6x+5y=18\\6x+y=6\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=3\\x=\dfrac{1}{2}\end{matrix}\right.\)

Answer 3

\(\left\{{}\begin{matrix}3x+\dfrac{5}{2}y=9\\2x+\dfrac{1}{3}y=2\left(2\right)\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=3-\dfrac{5}{6}y\left(1\right)\\2x+\dfrac{1}{3}y=2\left(2\right)\end{matrix}\right.\\ Thay\left(1\right)vô\left(2\right)\\ 2\left(3-\dfrac{5}{6}y\right)+\dfrac{1}{3}y=2\\ \Leftrightarrow6-\dfrac{5}{3}y+\dfrac{1}{3}y=2\\ \Leftrightarrow y=3\Rightarrow x=3-\dfrac{5}{6}.3=\dfrac{1}{2}\)