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If |z(1)| = 2 and (1-i)z(2) + (1+i)bar(z...

If `|z_(1)| = 2 and (1-i)z_(2) + (1+i)bar(z)_(2) = 8 sqrt(2)`, then

A

minimum value of `|z_(1) - z_(2)|` is 1

B

minimum value of `|z_(1) - z_(2)|` is 2

C

maximum value of `|z_(1) - z_(2)|` is 8

D

maximum value of `|z_(1) - z_(2)|` is 4

Text Solution

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The correct Answer is:
To solve the problem step by step, we need to analyze the given conditions and derive the required values. ### Step 1: Understand the Given Conditions We have two complex numbers, \( z_1 \) and \( z_2 \). The modulus of \( z_1 \) is given as \( |z_1| = 2 \). This means that \( z_1 \) lies on a circle of radius 2 centered at the origin in the complex plane. ### Step 2: Rewrite the Equation The equation given is: \[ (1 - i)z_2 + (1 + i)\overline{z_2} = 8\sqrt{2} \] Let’s express \( z_2 \) in terms of its real and imaginary parts: \[ z_2 = x_2 + iy_2 \] Then, the conjugate \( \overline{z_2} \) is: \[ \overline{z_2} = x_2 - iy_2 \] Substituting these into the equation gives: \[ (1 - i)(x_2 + iy_2) + (1 + i)(x_2 - iy_2) = 8\sqrt{2} \] ### Step 3: Expand the Equation Expanding both parts: \[ (1 - i)(x_2 + iy_2) = x_2 + iy_2 - ix_2 - y_2 = (x_2 + y_2) + i(y_2 - x_2) \] \[ (1 + i)(x_2 - iy_2) = x_2 - iy_2 + ix_2 + y_2 = (x_2 + y_2) + i(x_2 - y_2) \] Adding these results: \[ 2(x_2 + y_2) + i(y_2 - x_2 + x_2 - y_2) = 2(x_2 + y_2) \] Setting this equal to \( 8\sqrt{2} \): \[ 2(x_2 + y_2) = 8\sqrt{2} \] Dividing both sides by 2: \[ x_2 + y_2 = 4\sqrt{2} \] ### Step 4: Interpret the Result The equation \( x_2 + y_2 = 4\sqrt{2} \) represents a line in the complex plane. ### Step 5: Find the Minimum and Maximum Values of \( |z_1 - z_2| \) To find the minimum and maximum values of \( |z_1 - z_2| \), we need to consider the distance from the center of the circle (the origin) to the line \( x_2 + y_2 = 4\sqrt{2} \). ### Step 6: Calculate the Distance from the Origin to the Line The line can be rewritten in the standard form: \[ x + y - 4\sqrt{2} = 0 \] Using the distance formula from a point to a line \( Ax + By + C = 0 \): \[ \text{Distance} = \frac{|Ax_0 + By_0 + C|}{\sqrt{A^2 + B^2}} \] Here, \( A = 1, B = 1, C = -4\sqrt{2}, (x_0, y_0) = (0, 0) \): \[ \text{Distance} = \frac{|0 + 0 - 4\sqrt{2}|}{\sqrt{1^2 + 1^2}} = \frac{4\sqrt{2}}{\sqrt{2}} = 4 \] ### Step 7: Determine Minimum and Maximum Distances - The minimum distance from the origin to the line is \( 4 \). - Since \( |z_1| = 2 \), the minimum value of \( |z_1 - z_2| \) is: \[ \text{Minimum} = \text{Distance to line} - \text{Radius} = 4 - 2 = 2 \] - The maximum value of \( |z_1 - z_2| \) is: \[ \text{Maximum} = \text{Distance to line} + \text{Radius} = 4 + 2 = 6 \] ### Conclusion Thus, the minimum value of \( |z_1 - z_2| \) is 2 and the maximum value is 6.
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