Given,
S=z∈C:z2+zˉ=0
Let z=x+iy
z2=x2−y2+2ixy
zˉ=x−iy
Now putting the value in z2+zˉ we get,
z2+zˉ=x2−y2+x+i(2xy−y)=0
Now on comparing both side we get,
⇒x2+x−y2=0 and 2xy−y=0
⇒y=0 or x=21
Now if y=0;x=0,−1
If x=21then y=23,2−3
So, z∈S∑(Re(z)+Im(z)=(0−1+21+21)+0+0+23−23)=0