If 2x2 + λxy + 2y2 + (λ – 4) x + 6y – 5 = 0 is the equation of a circle, then its radius is

Given that the equation of the circle is:


2x2 + λxy + 2y2 + (λ - 4)x + 6y - 5 = 0 ..... (1)


Comparing with the standard equation of circle:


x2 + y2 + 2ax + 2by + c = 0


We get


λ = 0


Substituting λ value in (1), we get


2x2 + 0xy + 2y2 + (0 - 4)x + 6y - 5 = 0


2x2 + 2y2 - 4x + 6y - 5 = 0



We know that for a circle x2 + y2 + 2ax + 2by + c = 0


Centre = (- a, - b)


Radius =


Radius (r) =





The correct option is (d)

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