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The real value of ‘a’ for which 3i3 – 2ai2 + (1 – a)i + 5 is real is ______.

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Question

The real value of ‘a’ for which 3i3 – 2ai2 + (1 – a)i + 5 is real is ______.

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Solution

The real value of ‘a’ for which 3i3 – 2ai2 + (1 – a)i + 5 is real is – 2.

Explanation:

3i3 – 2ai2 + (1 – a)i + 5 = –3i + 2a + 5 + (1 – a)i

= 2a + 5 + (–a – 2)i

which is real if –a – 2 = 0

i.e. a = –2.

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Chapter 5: Complex Numbers and Quadratic Equations - Solved Examples [Page 83]

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NCERT Exemplar Mathematics Exemplar [English] Class 11
Chapter 5 Complex Numbers and Quadratic Equations
Solved Examples | Q 16.(i) | Page 83

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