Question
Question: If \| z<sup>2</sup> – 1\| = \| z \|<sup>2</sup> + 1 then z lies on a –...
If | z2 – 1| = | z |2 + 1 then z lies on a –
A
Circle
B
Parabola
C
Ellipse
D
None of these
Answer
None of these
Explanation
Solution
Sol. On putting z = x + iy the equation is same as
| x2 – y2 + 2ixy – 1| = x2 + y2 + 1
Ž (x2 – y2 – 1)2 + 4x2y2 = (x2 + y2 + 1)2
Ž x = 0
Ž z lies on imaginary axis, so (A), (B), (C) are ruled out.