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If z = x + iy, then show that z z¯+2(z+z¯)+b = 0, where b ∈ R, represents a circle.

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Question

If z = x + iy, then show that `z  barz + 2(z + barz) + b` = 0, where b ∈ R, represents a circle.

Sum
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Solution

Given that: z = x + iy

To prove: `z  barz + 2(z + barz) + b` = 0

⇒ (x + iy) (x – iy) + 2(x + iy + x – iy) + b = 0

⇒ x2 + y2 – 2(x + x) + b = 0

⇒ x2 + y2 – 4x + b = 0

Which represents a circle.

Hence proved.

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Chapter 5: Complex Numbers and Quadratic Equations - Exercise [Page 91]

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NCERT Exemplar Mathematics [English] Class 11
Chapter 5 Complex Numbers and Quadratic Equations
Exercise | Q 8 | Page 91

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