\(\left\{{}\begin{matrix}6x+6y=5xy(1)\\\dfrac{4}{x}-\dfrac{3}{y}=1\end{matrix}\right.\)
Chia 2 vế cho xy thì (1)(vì `x,y ne 0`)
`<=>` $\begin{cases}\dfrac6x+\dfrac6y=5\\\dfrac{4}{x}-\dfrac{3}{y}=1\\\end{cases}$
`<=>` $\begin{cases}\dfrac6x+\dfrac6y=5\\\dfrac{8}{x}-\dfrac{6}{y}=2\\\end{cases}$
`<=>` $\begin{cases}\dfrac{14}{x}=7\\\dfrac6x+\dfrac6y=5\\\end{cases}$
`<=>` $\begin{cases}\dfrac{14}{x}=7\\\dfrac6x+\dfrac6y=5\\\end{cases}$
`<=>` $\begin{cases}x=2\\y=3\\\end{cases}$
Vậy HPT có nghiệm (x,y)=(2,3)
\(\left\{{}\begin{matrix}3x-3y=5\\5x+2y=23\end{matrix}\right.< =>\left\{{}\begin{matrix}6x-6y=10\\15x+6y=69\end{matrix}\right.< =>\left\{{}\begin{matrix}21x=79\\3x-3y=5\end{matrix}\right.\)
\(\left\{{}\begin{matrix}x=\dfrac{79}{21}\\y=\dfrac{44}{21}\end{matrix}\right.\)
vậy hệ pt có nghiệm (x,y)=(\(\dfrac{79}{21};\dfrac{44}{21}\))
