JEE Advanced2007MathematicsComplex NumberActual
If |z|=1 and z 1 , then all the values of z 1-z^2 lie on
Options
- Aa line not passing through the origin
- B|z|= 2
- Cthe X-axis
- Dthe Y-axis
Correct answer
D. the Y-axis
Step-by-step solution
Let z= +i aligned z 1-z^2 & = +i 1-( 2 +i 2 ) & = +i 2 ^2 -2 i & = +i -2 i ( +i ) & = i 2 aligned Hence, z 1-z^2 lies on the imaginary axis, i.e. x=0 . ALITER Let E= z 1-z^2 = z z z -z^2 = 1 z -z which is imaginary.