\(\hept{\begin{cases}x+xy+y=5\\x^2+y^2=5\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}x+y=5-xy\\\left(x+y\right)^2-2xy=5\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}x+y=5-xy\\25-10xy+\left(xy\right)^2-2xy=5\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}x+y=5-xy\\\left(xy\right)^2-12xy+20=0\end{cases}}\)
\(\Leftrightarrow\hept{\begin{cases}x+y=5-xy\\\orbr{\begin{cases}xy=2\\xy=10\end{cases}}\end{cases}}\)\(\hept{\begin{cases}x+y=5-xy\\\orbr{\begin{cases}xy=2\\xy=10\end{cases}}\end{cases}}\)
TH1 \(xy=2\Rightarrow x+y=3\)
\(\rightarrow\left(x,y\right)=\left(1,2\right)\left(2,1\right)\)
TH2 \(xy=10\Rightarrow x+y=-5\)
HPTVN
Vậy No of hệ \(\left(1,2\right)\left(2,1\right)\)
trog bài có j sai thì ns cho mk nhé
