\(\left\{{}\begin{matrix}x+y+2z=4\\2x-y+3x=6\\x-3y+4z=7\end{matrix}\right.\)
\(\left\{{}\begin{matrix}x+y+z=23\\y+z+t=31\\z+t+x=27\\t+x+y=33\end{matrix}\right.\)
\(\left\{{}\begin{matrix}\dfrac{xy}{x+y}=\dfrac{8}{3}\\\dfrac{yz}{y+z}=\dfrac{12}{5}\\\dfrac{xz}{x+z}=\dfrac{24}{7}\end{matrix}\right.\)
Giải theo cách lớp 9 nhé. Cảm ơn mn