Question

giải hệ PT

x-2y=3

2x+3y=-1

Answer 1

\(\left\{{}\begin{matrix}x-2y=3\\2x+3y=-1\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=3+2y\\2\left(3+2y\right)+3y=-1\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=3+2y\\6+4y+3y=-1\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=3+2y\\7y=-7\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=3+2\left(-1\right)\\y=-1\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=1\\y=-1\end{matrix}\right.\)

Answer 2

\(\Leftrightarrow\left\{{}\begin{matrix}2x-4y=6\\2x+3y=-1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=-1\\x=3+2y=3-2=1\end{matrix}\right.\)