if 2x2+y2+4λx+λ2=0 represents a circle of
meaningful radius, then the range of real values of λ., is
R
(0, ∞)
(−∞, 0)
none of these
We have
2x2+y2+4λx+λ2=0⇒x2+y2+2λx+λ22=0
This equation will represent a circle of meaningful radius if
λ2+0−λ22≥0⇒λ22≥0 which is true for all λ∈R