\(A=\frac{x^2}{y}+\frac{y^2}{x}=\frac{x^3+y^3}{xy}\)
Theo bunhia ta có:\(\left(x^3+y^3\right)\left(x+y\right)\ge\left(x^2+y^2\right)^2=4\)
Mà \(\left(x+y\right)^2\le2\left(x^2+y^2\right)=4\)
\(\Rightarrow0< x+y\le2\)
\(\Rightarrow x^3+y^3\ge2\)
Lại có:\(xy\le\frac{x^2+y^2}{2}=1\)
\(\Rightarrow A\ge\frac{2}{1}=2\)
"="<=>x=y=1