Bài 1:
a: Ta có: \(\left\{{}\begin{matrix}7x+4y=2\\5x-2y=16\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}7x+4y=2\\10x-4y=32\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}17x=34\\5x-2y=16\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=2\\2y=5x-16=-6\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=-3\end{matrix}\right.\)
b) Ta có: \(\left\{{}\begin{matrix}2x+3y=19\\3x+4y=-14\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}6x+9y=57\\6x+8y=-28\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=85\\2x=19-3\cdot85=-236\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=-118\\y=85\end{matrix}\right.\)
c) Ta có: \(\left\{{}\begin{matrix}2x+2y=3\\3x-2y=2\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}5x=5\\2x+2y=3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=1\\y=\dfrac{1}{2}\end{matrix}\right.\)
