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Answer the following: Show that 1-2i3-4i+1+2i3+4i is real

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Question

Answer the following:

Show that `(1 - 2"i")/(3 - 4"i") + (1 + 2"i")/(3 + 4"i")` is real

Sum
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Solution

`(1 - 2"i")/(3 - 4"i") + (1 + 2"i")/(3 + 4"i")`

= `((1 - 2"i")(3 + 4"i") + (3 - 4"i")(1 + 2"i"))/((3 + 4"i")(3 - 4"i"))`

= `(3 + 4"i" - 6"i" - 8"i"^2 + 3 + 6"i" - 4"i" - 8"i"^2)/(9 - 16"i"^2)`

= `(6 - 16"i"^2)/(9 - 16(-1))`

= `(6 - 16(-1))/(9 + 16)`    ...[∵ i2 = – 1]

= `22/25`, which is a real number.

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Chapter 1: Complex Numbers - Miscellaneous Exercise 1.2 [Page 22]

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Balbharati Mathematics and Statistics 2 (Arts and Science) [English] Standard 11 Maharashtra State Board
Chapter 1 Complex Numbers
Miscellaneous Exercise 1.2 | Q II.15 | Page 22

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