Let z and w be two complex numbers such that w = z z ¯ - 2 z + 2 , z + i z - 3 i = 1 and Re w has…

Let z and w be two complex numbers such that w=zz¯-2z+2,z+iz-3i=1 and Rew has minimum value. Then, the minimum value of nN for which wn is real, is equal to _______.

Solution

ω=zz¯-2z+2

z+iz-3i=1

z+i=z-3i

x2+y+12=x2+y-32

y=1

z=x+i, xR

ω=x+ix-i-2x+i+2

=x2+1-2x-2i+2

Reω=x2-2x+3=x-12+2

For min Reω, x=1

ω=2-2i=21-i=22e-iπ4

ωn=22ne-inπ4

For real and minimum value of n,

n=4

Asked in: JEE Main 2021 (16 Mar Shift 1)

Practice more Complex Number questions on Aicharya