Question

Bai 2: cho hpt \(\left\{{}\begin{matrix}x-2y=4m-5\\2x+y=3m\end{matrix}\right.\)

a) giai pt khi m=3

b) Tim de pt co nghiem (x,y) thoa man 2x−1y=−12x−1y=−1

(mink dag can gap)

Answer 1

a. 

⇔ \(\left\{{}\begin{matrix}x-2y=4.3-5\\2x+y=3.3\end{matrix}\right.\)

⇔ \(\left\{{}\begin{matrix}x-2y=7\\2x+y=9\end{matrix}\right.\)

⇔ \(\left\{{}\begin{matrix}-2x+4y=-14\\2x+y=9\end{matrix}\right.\)

⇔ \(\left\{{}\begin{matrix}5y=-5\\2x+y=9\end{matrix}\right.\)

⇔ \(\left\{{}\begin{matrix}y=-1\\2x-1=9\end{matrix}\right.\)

⇔ \(\left\{{}\begin{matrix}y=-1\\x=5\end{matrix}\right.\)

Vậy nghiệm của hpt là: (5;1)