Question

Tìm 2 số x,y sao chõ+y = xy = x:y (y khác 0)

Answer 1

Ta có

\(x+y=xy\\ \Leftrightarrow xy-x-y=0\\ \Leftrightarrow x\left(y-1\right)-y+1=1\\ \Leftrightarrow x\left(y-1\right)-\left(y-1\right)=1\\ \Leftrightarrow\left(x-1\right)\left(y-1\right)=1\\ \Rightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x-1=1\\y-1=1\end{matrix}\right.\\\left\{{}\begin{matrix}x-1=-1\\y-1=-1\end{matrix}\right.\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x=2\\y=2\end{matrix}\right.\\\left\{{}\begin{matrix}x=0\\y=0\end{matrix}\right.\end{matrix}\right.\)

Vì y khác 0 nên x = y =2

Vậy x = y = 2.

P/s: Hình như vế sau sai hay sao ấy ?!