Bài 2A
a, \(\left\{{}\begin{matrix}3y-15+2x-6=0\\7x-28+3x+3y-3-14=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2x+3y=21\\10x+3y=45\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}8x=24\\y=\dfrac{21-2x}{3}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=3\\y=5\end{matrix}\right.\)
b, \(\left\{{}\begin{matrix}xy-x+y-1=xy+x-2y-2-1\\2xy-4y=2xy-3\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}2x-3y-2=0\\y=\dfrac{3}{4}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{17}{8}\\y=\dfrac{3}{4}\end{matrix}\right.\)
2B
a, \(\left\{{}\begin{matrix}5x+10y-3x+3y=99\\6x-y=17\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2x+13y=99\\6x-y=17\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=4\\y=7\end{matrix}\right.\)
b, \(\left\{{}\begin{matrix}xy-x+y-1=xy-1\\xy-3x-3y+9=xy-3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}-x+y=0\\-3x-3y=-12\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=2\end{matrix}\right.\)
