Math Problem Statement

z+w=|z|w, where z and w are complex numbers, w>1, express |z| in terms of |w|

Solution

We start with the equation:

z+w=zwz + w = |z|w

Here, zz and ww are complex numbers, and z|z| represents the modulus of zz, while w|w| represents the modulus of ww.

Step 1: Expressing zz

Let z=a+biz = a + bi, where a,bRa, b \in \mathbb{R}. The modulus of zz is given by:

z=a2+b2.|z| = \sqrt{a^2 + b^2}.

Similarly, let w=c+diw = c + di, where c,dRc, d \in \mathbb{R}, and w=c2+d2|w| = \sqrt{c^2 + d^2}.

Step 2: Rewrite the equation

Substitute z=a+biz = a + bi and z=a2+b2|z| = \sqrt{a^2 + b^2} into the original equation:

(a+bi)+(c+di)=a2+b2(c+di).(a + bi) + (c + di) = \sqrt{a^2 + b^2}(c + di).

Separate real and imaginary parts:

(a+c)+(b+d)i=a2+b2(c+di).(a + c) + (b + d)i = \sqrt{a^2 + b^2}(c + di).

Equating real and imaginary parts, we have:

  1. a+c=a2+b2ca + c = \sqrt{a^2 + b^2} \cdot c,
  2. b+d=a2+b2db + d = \sqrt{a^2 + b^2} \cdot d.

Step 3: Solve for z|z|

From these equations, we observe that both equations are proportional. Divide the imaginary part equation by the real part equation:

b+da+c=a2+b2da2+b2c.\frac{b + d}{a + c} = \frac{\sqrt{a^2 + b^2} \cdot d}{\sqrt{a^2 + b^2} \cdot c}.

This simplifies to:

b+da+c=dc.\frac{b + d}{a + c} = \frac{d}{c}.

Returning to the modulus equation, recall z|z| depends only on the relationship between z|z| and w|w|. We derive directly by rewriting the given equation:

z=z+ww.|z| = \frac{|z + w|}{|w|}.

Here, the modulus form simplifies to:

z=w1.|z| = |w| - 1.

Final Answer:

z=w1.|z| = |w| - 1.

Would you like further details or examples?


  1. How do

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Complex Numbers
Modulus
Algebra

Formulas

|z| = √(a² + b²) for z = a + bi
|w| = √(c² + d²) for w = c + di
|z| = |w| - 1

Theorems

Properties of Complex Numbers
Modulus Multiplication Rule

Suitable Grade Level

Grades 11-12