∵ z2=z.21−∣z∣ ...... (1)
⇒∣z∣2=∣z∣.21−∣z∣
⇒∣z∣=21−∣z∣ ,
∵ b=0⇒∣z∣=0
∴ ∣z∣=1 ...... (2)
∵ z=a+ib then a2+b2=1 ...... (3)
Now again from equation (1), equation (2), equation (3) we get :
a2−b2+i2ab=(a−ib)20
∴ a2−b2=a and 2ab=−b
∴ a=−21 and b=±23
z=−21+23i or z=−21−23i
zn=(z+1)n⇒(zz+1)n=1
(1+z1)n=1
(21+3i)=1 , then minimum value of n is 6.