Question

Giải hệ phương trình :

\(\left\{{}\begin{matrix}5x-3y=9\\3x+2y=7\end{matrix}\right.\)

Answer 1

\(\Leftrightarrow\left\{{}\begin{matrix}10x-6y=18\\9x+6y=21\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}19x=39\\10x-6y=18\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{39}{19}\\10.\dfrac{39}{19}-6y=18\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{39}{19}\\y=\dfrac{8}{19}\end{matrix}\right.\)

Answer 2

\(\left\{{}\begin{matrix}5x-3y=9\\3x+2y=7\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}10x-6y=18\\9x+6y=21\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}19x=39\\3x+2y=7\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{39}{19}\\3.\dfrac{39}{19}+2y=7\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{39}{19}\\\dfrac{117}{19}+2y=7\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{39}{19}\\2y=\dfrac{16}{19}\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{39}{19}\\y=\dfrac{8}{19}\end{matrix}\right.\)