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Statement-1 : IF |z+1/z| =a , where z is...

Statement-1 : IF `|z+1/z|` =a , where z is a complex number and a is a real number, the least and greatest values of |z| are ` (sqrt(a^(2)+4-a))/2 and (sqrt(a^(2)+ 4)+a)/2`
and Statement -2 : For a equal ot zero the greatest and the least values of |z| are equal .

A

(a)Statement -1 is True, Statement -2 is True, Statement -2 is a correct explanation for statement -8

B

(b)Statement -1 is True, Statement -2 is True , Statement -2 is NOT a correct explanation for Statement -8

C

(c)Statement -1 is True, Statement -2 is False

D

(d)Statement -1 is Flase, Statement -2 is True

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the given statements about the complex number \( z \) and its modulus. Let's break down the solution step by step. ### Step 1: Understanding the Given Condition We start with the condition: \[ |z + \frac{1}{z}| = a \] where \( z \) is a complex number and \( a \) is a real number. ### Step 2: Expressing \( z \) Let \( z = re^{i\theta} \) where \( r = |z| \) (the modulus of \( z \)) and \( \theta \) is the argument of \( z \). Then, we can express \( \frac{1}{z} \) as: \[ \frac{1}{z} = \frac{1}{re^{i\theta}} = \frac{1}{r} e^{-i\theta} \] ### Step 3: Substitute into the Condition Substituting \( z \) and \( \frac{1}{z} \) into the modulus condition gives: \[ |re^{i\theta} + \frac{1}{r} e^{-i\theta}| = a \] ### Step 4: Simplifying the Expression Using the properties of modulus: \[ |re^{i\theta} + \frac{1}{r} e^{-i\theta}| = |r + \frac{1}{r} e^{-2i\theta}| \] This can be simplified further using the triangle inequality, but we will focus on the modulus directly. ### Step 5: Finding the Bounds for \( |z| \) To find the least and greatest values of \( |z| \), we can rewrite the equation: \[ |z|^2 + 1 = a|z| \] Let \( r = |z| \). This leads us to the quadratic equation: \[ r^2 - ar + 1 = 0 \] ### Step 6: Using the Quadratic Formula The roots of the quadratic equation can be found using the quadratic formula: \[ r = \frac{a \pm \sqrt{a^2 - 4}}{2} \] This gives us the least and greatest values of \( |z| \): - Least value: \( \frac{a - \sqrt{a^2 - 4}}{2} \) - Greatest value: \( \frac{a + \sqrt{a^2 - 4}}{2} \) ### Step 7: Analyzing Statement 1 We need to check if the least and greatest values match the expressions given in Statement 1: - Least value: \( \frac{\sqrt{a^2 + 4 - a}}{2} \) - Greatest value: \( \frac{\sqrt{a^2 + 4} + a}{2} \) ### Step 8: Analyzing Statement 2 For \( a = 0 \): - The least and greatest values become equal: \[ |z| = 1 \] This confirms Statement 2. ### Conclusion Both statements are true. The least and greatest values of \( |z| \) are correctly given in Statement 1, and for \( a = 0 \), the least and greatest values of \( |z| \) are indeed equal, confirming Statement 2.
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