Normal
2.Áp dụng bđt Bu-nhi ta có : \[(1+x)(1+\frac{y}{x}) \ge (1+\sqrt{y})^2\] \[\Rightarrow A \ge (1+\sqrt{y})^2.(1+\frac{9}{\sqrt{y}}^2) \ge (1+3)^2\]Do đó: \[A \ge 16\]
2.Áp dụng bđt Bu-nhi ta có : \[(1+x)(1+\frac{y}{x}) \ge (1+\sqrt{y})^2\]
\[\Rightarrow A \ge (1+\sqrt{y})^2.(1+\frac{9}{\sqrt{y}}^2) \ge (1+3)^2\]
Do đó: \[A \ge 16\]
