Question

77. The equation lz - il + 12+ il =k, a > 0, can represent an ellipse if k is
(a) 1
(b) 2
(c) 4
(d) none of these
​

Answer 1

Let SandS'SandS′ be two foci of the ellipse x2a3+y2b2=1x2a3+y2b2=1 . If a circle described on SS′SS′ as diameter intersects the ellipse at real and distinct points, then the eccentricityeeof the ellipse satisfies c=12–√c=12 (b) e∈(12–√,1)e∈(12,1)e∈(0,12–√)e∈(0,12) (d) none of these