$\begin{cases}5x-y=5\\y-4x=1\end{cases}$
`<=>` $\begin{cases}\5x-y+y-4x=6\\y-4x=1end{cases}$
`<=>` $\begin{cases}x=6\\y=1+4x=25\end{cases}$
Vậy HPT có nghiệm `(x,y)=(6,25)`
$\begin{cases}5x-y=5\\y-4x=1\end{cases}$
`<=>` $\begin{cases}\5x-y+y-4x=6\\y-4x=1\end{cases}$
`<=>` $\begin{cases}x=6\\y=1+4x=25\end{cases}$
Vậy HPT có nghiệm `(x,y)=(6,25)`
\(\left\{{}\begin{matrix}5x-y=5\\y-4x=1\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}5x-y=5\\-4x+y=1\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=6\\-4x+y=1\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=6\\-4.6+y=1\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=6\\-24+y=1\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x=6\\y=25\end{matrix}\right.\)
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