goi A(a,0),va B(0,b)
tu DK ta co OB=OA $\Rightarrow \Delta AOB $ vunong can tai O
 tu do ta co he so goc cua duong thang AB la k=$\pm  1$va co a=$\left| {b} \right|$
ta co phuong trinh duong thang AB la:y=k(x-x0)+y0
thay toa do diem M vao pt AB va co cac du kien tren thi ta tim dc  diem A va B 
( den day cac ban tu lam nha ........hjhjj
 

DK: X.Y khac 0
\(
\left\{ \begin{array}{l} 1+xy=\frac{6xy}{2x+y}\\ \frac{x^{2}+y^{2}}{(xy)^{2}}.(1+xy)=8\end{array} \right.\Leftrightarrow \left\{ \begin{array}{l} 1+xy=\frac{6xy}{2x+y}    (1)\\ \frac{x^{2}+y^{2}}{(xy)^{2}}.(\frac{6xy}{2x+y})^{2}=8       (2)\end{array} \right.
\)
giai 2 :(2)$\Leftrightarrow 0,5x^{2}+3,5y^{2}-4xy=0$      (3)
 ta thay y=o khong thoa man pt .do do ta chia ca 2 ve cho $y^{2}\Rightarrow $  pt 3 tro thanh pt bac 2 an  $\frac{x}{y}$ giai ra ta dc:
TH1 :$\frac{x}{y}=7$ 
TH2: $\frac{x}{y}=1$
(den day tu giai nha em.thay vao pt 1 la OK)