question_answer

If \[{{x}^{2}}+{{y}^{2}}=t-\frac{1}{t}\] and \[{{x}^{4}}+{{y}^{4}}={{t}^{2}}+\frac{1}{{{t}^{2}}},\] then the value of \[{{x}^{3}}y\frac{dy}{dx}=\]

A)  2                    

B)  1             

C)  0            

D)  None of these