Cho \(x=1+{{a}^{2}},y=1+{{a}^{-2}}\left( \forall...

Câu hỏi:  Cho \(x=1+{{a}^{2}},y=1+{{a}^{-2}}\left( \forall a\in \mathbb{R},a>0 \right)\). Khi đó thì :

A  \(y=\frac{1}{x}\)                               

B  \(y=\frac{x}{x-1}\)                

C  \(y=\frac{x-1}{x}\)                                        

D  \(y=1+\frac{1}{x}\)