hallo
a)
z = x + iy
z* = x - iy
Re(z) = x
Im(z*) = -y
Re(z) + Im(z*) = 0
x - y = 0
x = y
L = {z∈ℂ | Re(z) = Im(z)}
b)
(x+iy)*(x-iy) = -Im(4/i)
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NR
4/i = (4(-i))/(i(-i)) = -4i/-i² = -4i/(-(-1)) = -4i
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(x+iy)*(x-iy) = -Im(-4i)
x²+y² = -(-4)
x²+y² = 4
y = ±√(4-x²)
L = {z∈ℂ | Im(z) = ±√(4-x²), x<=2 }