Question

Giải hệ phương trình 
{ x - 2y = -3
{ 5x + 4y = 6

Answer 1

\(\left\{{}\begin{matrix}x-2y=-3\\5x+4y=6\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=2y-3\\5\left(2y-3\right)+4y=6\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=2y-3\\10y-15+4y=6\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=2y-3\\14y=21\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=2.\dfrac{3}{2}-3\\y=\dfrac{3}{2}\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}x=0\\y=\dfrac{3}{2}\end{matrix}\right.\)