question_answer

The equation \[{{x}^{2}}+{{k}_{1}}{{y}^{2}}+{{k}_{2}}xy=0\] represents a pair of perpendicular lines, if  

A)            \[{{k}_{1}}=-1\]                   

B)            \[{{k}_{1}}=2{{k}_{2}}\]

C)            \[2{{k}_{1}}={{k}_{2}}\]   

D)            None of these