Home
Class 12
MATHS
For the complex number z satisfying the ...

For the complex number z satisfying the condition `|z+(2)/(z)|=2`, the maximum value of `|z|` is

A

`sqrt3-1`

B

`sqrt3+1`

C

`sqrt2+sqrt3`

D

`sqrt3`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the maximum value of \( |z| \) given the condition \( |z + \frac{2}{z}| = 2 \). ### Step-by-Step Solution: 1. **Rewrite the Condition**: We start with the condition: \[ |z + \frac{2}{z}| = 2 \] Let \( z = r e^{i\theta} \) where \( r = |z| \) and \( \theta \) is the argument of \( z \). 2. **Substituting \( z \)**: Substitute \( z \) into the equation: \[ |r e^{i\theta} + \frac{2}{r e^{i\theta}}| = 2 \] This simplifies to: \[ |r e^{i\theta} + \frac{2}{r} e^{-i\theta}| = 2 \] 3. **Combine the Terms**: We can express the left-hand side in terms of real and imaginary parts: \[ |r \cos \theta + \frac{2}{r} \cos \theta + i \left( r \sin \theta - \frac{2}{r} \sin \theta \right)| = 2 \] This can be simplified to: \[ |(r + \frac{2}{r}) \cos \theta + i (r - \frac{2}{r}) \sin \theta| = 2 \] 4. **Using the Modulus**: The modulus can be expressed as: \[ \sqrt{(r + \frac{2}{r})^2 \cos^2 \theta + (r - \frac{2}{r})^2 \sin^2 \theta} = 2 \] 5. **Square Both Sides**: Squaring both sides gives: \[ (r + \frac{2}{r})^2 \cos^2 \theta + (r - \frac{2}{r})^2 \sin^2 \theta = 4 \] 6. **Expanding the Squares**: Expanding both terms: \[ (r^2 + 4 + \frac{4}{r^2}) \cos^2 \theta + (r^2 - 4 + \frac{4}{r^2}) \sin^2 \theta = 4 \] 7. **Combining Terms**: Combine the terms: \[ r^2 (\cos^2 \theta + \sin^2 \theta) + 4(\cos^2 \theta - \sin^2 \theta) + \frac{4}{r^2} (\cos^2 \theta + \sin^2 \theta) = 4 \] Since \( \cos^2 \theta + \sin^2 \theta = 1 \): \[ r^2 + 4(\cos^2 \theta - \sin^2 \theta) + \frac{4}{r^2} = 4 \] 8. **Rearranging**: Rearranging gives: \[ r^2 + \frac{4}{r^2} + 4(\cos^2 \theta - \sin^2 \theta) = 4 \] 9. **Setting \( t = |z| = r \)**: Let \( t = |z| \): \[ t^2 + \frac{4}{t^2} + 4(\cos^2 \theta - \sin^2 \theta) = 4 \] 10. **Finding Maximum Value**: To maximize \( t \), we analyze the quadratic: \[ t^2 - 2t + 2 \leq 0 \] The roots of this equation can be found using the quadratic formula: \[ t = 1 \pm \sqrt{3} \] Since \( t \) must be non-negative, we take: \[ t \leq 1 + \sqrt{3} \] ### Conclusion: Thus, the maximum value of \( |z| \) is: \[ \boxed{1 + \sqrt{3}} \]
Promotional Banner

Similar Questions

Explore conceptually related problems

Find the greatest value of the moduli of complex numbers z satisfying the equation |z-(4)/(z)|=2 . What is the minimum value ?

The complex number z satisfies thc condition |z-25/z|=24 . The maximum distance from the origin of co-ordinates to the points z is

Find a complex number z satisfying the equation z+sqrt(2)|z+1|+i=0.

Find a complex number z satisfying the equation z+sqrt(2)|z+1|+i=0.

Find a complex number z satisfying the equation z+sqrt(2)|z+1|+i=0.

If z is any complex number satisfying |z-3-2i|lt=2 then the maximum value of |2z-6+5i| is

If z is a complex number satisfying the equaiton z^(6) - 6z^(3) + 25 = 0 , then the value of |z| is

Find the non-zero complex number z satisfying z =i z^2dot

If z is a complex number satisfying |z^(2)+1|=4|z| , then the minimum value of |z| is

Let z be a complex number satisfying the equation (z^3+3)^2=-16 , then find the value of |z|