\(\Leftrightarrow\left\{{}\begin{matrix}xy+x+y+1=6\\\left(x+1\right)^3+\left(y+1\right)^3=35\end{matrix}\right.\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left(x+1\right)\left(y+1\right)=6\\\left(x+1\right)^3+\left(y+1\right)^3=35\end{matrix}\right.\)
Đặt \(\left\{{}\begin{matrix}x+1=a\\y+1=b\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}ab=6\\a^3+b^3=35\end{matrix}\right.\)
\(\Rightarrow a^3+\left(\frac{6}{a}\right)^3=35\Rightarrow\left(a^3\right)^2-35.a^3+216=0\)
\(\Rightarrow\left[{}\begin{matrix}a^3=27\\a^3=8\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}a=2;b=3\\a=3;b=2\end{matrix}\right.\)
\(\Rightarrow...\)
