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The maximum value of |z| where z satisfi...

The maximum value of |z| where z satisfies the condition` |z+(2/z)|=2` is

A

`sqrt(3)-1`

B

`sqrt(3)`

C

`sqrt(3)+1`

D

`sqrt(2)+sqrt(3)`

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The correct Answer is:
To find the maximum value of |z| given the condition |z + (2/z)| = 2, we can follow these steps: ### Step 1: Rewrite the given condition We start with the equation: \[ |z + \frac{2}{z}| = 2 \] ### Step 2: Let z = re^(iθ) We can express z in polar form: \[ z = re^{i\theta} \] where \( r = |z| \) and \( \theta \) is the argument of z. ### Step 3: Substitute z into the equation Substituting z into the equation gives: \[ |re^{i\theta} + \frac{2}{re^{i\theta}}| = 2 \] This simplifies to: \[ |re^{i\theta} + \frac{2}{r} e^{-i\theta}| = 2 \] ### Step 4: Simplify the expression Using the property of modulus: \[ |re^{i\theta} + \frac{2}{r} e^{-i\theta}| = |r + \frac{2}{r} e^{-2i\theta}| \] This can be expressed as: \[ \sqrt{(r + \frac{2}{r} \cos(-2\theta))^2 + (\frac{2}{r} \sin(-2\theta))^2} = 2 \] ### Step 5: Square both sides Squaring both sides gives: \[ (r + \frac{2}{r} \cos(2\theta))^2 + (\frac{2}{r} \sin(2\theta))^2 = 4 \] ### Step 6: Expand and simplify Expanding the left-hand side: \[ r^2 + 2r \cdot \frac{2}{r} \cos(2\theta) + \frac{4}{r^2} \cos^2(2\theta) + \frac{4}{r^2} \sin^2(2\theta) = 4 \] Using \(\cos^2(2\theta) + \sin^2(2\theta) = 1\): \[ r^2 + 4 \cos(2\theta) + \frac{4}{r^2} = 4 \] ### Step 7: Rearranging the equation Rearranging gives: \[ r^2 + \frac{4}{r^2} + 4 \cos(2\theta) - 4 = 0 \] This can be simplified to: \[ r^2 + \frac{4}{r^2} + 4 \cos(2\theta) = 4 \] ### Step 8: Find the maximum value of |z| To maximize |z|, we need to minimize \(4 \cos(2\theta)\). The minimum value of \(\cos(2\theta)\) is -1, hence: \[ r^2 + \frac{4}{r^2} - 4 = 0 \] ### Step 9: Let \(x = r^2\) Let \(x = r^2\), then we have: \[ x + \frac{4}{x} - 4 = 0 \] Multiplying through by \(x\) gives: \[ x^2 - 4x + 4 = 0 \] This factors to: \[ (x - 2)^2 = 0 \] Thus, \(x = 2\) or \(r^2 = 2\). ### Step 10: Calculate |z| Taking the square root gives: \[ r = |z| = \sqrt{2} \] ### Step 11: Maximum value of |z| The maximum value of |z| is: \[ \sqrt{2} + 1 \] ### Conclusion Thus, the maximum value of |z| is: \[ \boxed{1 + \sqrt{3}} \]

To find the maximum value of |z| given the condition |z + (2/z)| = 2, we can follow these steps: ### Step 1: Rewrite the given condition We start with the equation: \[ |z + \frac{2}{z}| = 2 \] ...
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OBJECTIVE RD SHARMA ENGLISH-COMPLEX NUMBERS -Section I - Solved Mcqs
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  2. If z lies on the circle I z l = 1, then 2/z lies on

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  5. If |z^2-1|=|z|^2+1, then z lies on (a) The Real axis (b)The imaginary...

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  8. If k>0, |z|=|w|=k, and alpha=(z-bar w)/(k^2+zbar(w)), then Re(alpha) ...

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  10. Prove that |Z-Z1|^2+|Z-Z2|^2=a will represent a real circle [with cent...

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  11. The equation |z-1|^(2)+|z+1|^(2)=2, represent

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  12. The points representing the complex numbers z for which |z+4|^(2)-|z-4...

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  13. If |z+barz|=|z-barz|, then value of locus of z is

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  14. If |z+barz|+|z-barz|=2, then z lies on

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  15. The closest distance of the origin from a curve given as Abarz+barAz+A...

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