Question:
If |z + 1| = z + 2 (1 + i), then find z.
Solution:
According to the question,
We have,
|z + 1| = z + 2 (1 + i)
Substituting z = x + iy, we get,
⇒ |x + iy + 1| = x + iy + 2 (1 + i)
We know,
|z| = √(x2 + y2)
√((x + 1)2 + y2) = (x + 2) + i(y + 1)
Comparing real and imaginary parts,
⇒ √((x + 1)2 + y2) = x + 2
And 0 = y + 2
⇒ y = -2
Substituting the value of y in √((x + 1)2 + y2) = x + 2,
⇒ (x + 1)2 + (-2)2 = (x + 2)2
⇒ x2 + 2x + 1 + 4 = x2 + 4x + 4
⇒ 2x = 1
Hence, x = ½
Hence, z = x + iy
= ½ – 2i