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Is (1 + i14 + i18 + i22) a real number? Justify your answer

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Question

Is (1 + i14 + i18 + i22) a real number? Justify your answer

Sum
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Solution

1+ i14 + i18 + i22

= 1 + (i4)3.i2 + (i4)4.i2 + (i4)5.i2

= 1+ (1)3 (–1) + (1)4 (–1) + (1)5 (–1)   ...[∵ i2 = – 1, i4 = 1]

= 1 – 1 – 1 – 1

= – 2, which is a real number.

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Chapter 1: Complex Numbers - Exercise 1.1 [Page 6]

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