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Question

What is the value of \(\sqrt{12+5 i}+\sqrt{12-5 i}\) where \(i=\sqrt{-1}\) ?

This question was previously asked in
NDA I 2023 GAT Previous Year Paper (16-Apr-2023)
The correct answer is

5√2

The principal roots are \(\sqrt{12+5i}=(5+i)/\sqrt2\) and \(\sqrt{12-5i}=(5-i)/\sqrt2\). Adding gives \(10/\sqrt2=5\sqrt2\).

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  1. What is the modulus of z?

  2. What is angle θ such that z is purely real ?

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Important Questions from Properties of Complex Numbers

  1. The Real part of \(z = \frac{{5 + 2i}}{{2 - 5i}} - \frac{{3 - 4i}}{{4 + 3i}} - \frac{1}{i}\) is

  2. What is the modulus of z?

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  4. What is angle θ such that z is purely imaginary ?

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