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Find a and b if 1a+ib = 3 – 2i

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Question

Find a and b if `1/("a" + "ib")` = 3 – 2i

Sum
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Solution

`1/("a" + "ib")` = 3 – 2i

∴ a + ib = `1/(3 - 2"i")` 

∴ a + ib = `1/(3 - 2"i") xx (3 + 2"i")/(3 + 2"i")`

∴ a + ib = `(3 + 2"i")/(9 - 4"i"^2)`

∴ a + ib = `(3 + 2"i")/(9 + 4)`   ...[∵ i2 = – 1]

∴ a + ib = `(3 + 2"i")/13 = 3/13 + 2/13 "i"`

Equating the real and imaginary parts separately, we get,

a = `3/13`, b = `2/13`

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

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