\(\left(x+1\right)^2y+\left(y+1\right)^2x=1\)
\(\Rightarrow y\left(x^2+2x+1\right)+x\left(y^2+2y+1\right)=1\)
\(\Rightarrow x^2y+2xy+y+xy^2+2xy+x=1\)
\(\Rightarrow xy\left(x+y\right)+4xy+\left(x+y+4\right)=5\)
\(\Rightarrow xy\left(x+y+4\right)+\left(x+y+4\right)=5\)
\(\Rightarrow\left(xy+1\right)\left(x+y+4\right)=5\)
Đến đây thì dễ rùi
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