Question

Answer 1

đk: \(xy\ge-1\)

\(hpt< =>\left\{{}\begin{matrix}\left(xy+1\right)-4\sqrt{xy+1}+4=0\\xy+x=6\end{matrix}\right.\)

<=> \(\left\{{}\begin{matrix}\left(\sqrt{xy+1}-2\right)^2=0\\xy+x=6\end{matrix}\right.\)

<=> \(\left\{{}\begin{matrix}\sqrt{xy+1}=2\\xy+x=6\end{matrix}\right.< =>\left\{{}\begin{matrix}xy=3\\xy+x=6\end{matrix}\right.< =>x=3< =>y=1\left(Tm\right)\)

KL: hpt có nghiệm (x;y) = (3;1)