Question

giải phương trình 

\(\begin{cases} 3x-2y=11\\ 4x-5y=3 \end{cases} \)

 

Answer 1

\(\left\{{}\begin{matrix}3x-2y=11\\4x-5y=3\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}15x-10y=55\\8x-10y=6\end{matrix}\right.\Leftrightarrow7x=49\Leftrightarrow x=7\)

Thay x = 7 vào 3x - 2y = 11 ta được:

\(3\cdot7-2y=11\Leftrightarrow y=5\)

Vậy (x;y) = (7;5)

Answer 2

\(\left\{{}\begin{matrix}3x-2y=11\\4x-5y=3\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}12x-8y=44\\12x-15y=9\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}7y=35\\12x-15y=9\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}y=5\\12x-15.5=9\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}y=5\\x=7\end{matrix}\right.\)