Đặt $t=\frac{x}{y}\implies t\ge 2$.Khi đó: $A=\frac{2x}{y}+\frac{y}{x}-2=2t+\frac{1}{t}-2=2(t+\frac{4}{t})-\frac{7}{t}-2\ge 8-\frac{7}{2}-2=\frac{-3}{2}$
Đặt $t=\frac{x}{y}\implies t\ge 2$.Khi đó: $A=\frac{2x}{y}+\frac{y}{x}-2=2t+\frac{1}{t}-2=2(t+\frac{4}{t})-\frac{7}{t}-2\ge 4-\frac{7}{2}-2=\frac{-3}{2}$
Đặt $t=\frac{x}{y}\implies t\ge 2$.Khi đó: $A=\frac{2x}{y}+\frac{y}{x}-2=2t+\frac{1}{t}-2=2(t+\frac{4}{t})-\frac{7}{t}-2\ge
8-\frac{7}{2}-2=\frac{-3}{2}$