If is purely imaginary number (z ≠ – 1), find the value of |z|.
Given:
⇒ is purely imaginary
⇒ Let us assume , where K is any real number
Let us assume z=x+iy
⇒
Multiplying and dividing with (x+1)-iy
⇒
⇒
⇒
We know that i2=-1
⇒
⇒
Equating Real and Imaginary parts on both sides we get
⇒
⇒ x2+y2-1=0
⇒ x2+y2=1
⇒
⇒ |z|=1
∴ |z|=1