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If z1 and z2 are complex numbers such that z1 + z2 is a real number, then z2 = ______.

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Question

If z1 and z2 are complex numbers such that z1 + z2 is a real number, then z2 = ______.

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Solution

If z1 and z2 are complex numbers such that z1 + z2 is a real number, then z2 = `underlinebb(barz_1)`.

Explanation:

Let z1 = x1 + iy1 and z2 = x2 + iy2

z1 + z2 = (x1 + iy2) + (x2 + iy2)

z1 + z2 = (x1 + x2) + (y1 + y2)i

If z1 + z2 is real then,

y1 + y2 = 0

⇒ y1 = –y2

∴ z2 = x2 – iy1

z2 = x1 – iy1    ......(When x1 = x2)

So z2 = `barz_1`

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Chapter 5: Complex Numbers and Quadratic Equations - Exercise [Page 93]

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NCERT Exemplar Mathematics Exemplar [English] Class 11
Chapter 5 Complex Numbers and Quadratic Equations
Exercise | Q 25.(vi) | Page 93

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