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Answer the following: Simplify the following and express in the form a + ib: (1+2i)(3+4i)(5+i)-1

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Question

Answer the following:

Simplify the following and express in the form a + ib:

`(1 + 2/"i")(3 + 4/"i")(5 + "i")^-1`

Sum
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Solution

`(1 + 2/"i")(3 + 4/"i")(5 + "i")^-1`

= `(("i" + 2))/"i".((3"i" + 4))/"i". 1/(5 + "i")`

= `(3"i"^2 + 4"i" + 6"i" + 8)/("i"^2(5 + "i"))`

= `(-3 + 10"i" + 8)/(-1(5 + "i"))`  ...[∵ i2 = – 1]

= `((5 + 10"i"))/(-(5 + "i")`

= `((5 + 10"i")(5 - "i"))/(-(5 + "i")(5 - "i"))`

= `(25 - 5"i" + 50"i" - 10"i"^2)/(-(25 - "i"^2)`

= `(25 + 45"i" - 10(-1))/(-[25 - (-1)]`

= `(35 + 45"i")/(-26)`

= `(-35)/26 - 45/26"i"`

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Chapter 1: Complex Numbers - Miscellaneous Exercise 1.2 [Page 21]

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Balbharati Mathematics and Statistics (Arts and Science) Part 2 [English] Standard 11 Maharashtra State Board
Chapter 1 Complex Numbers
Miscellaneous Exercise 1.2 | Q II. (1) (vii) | Page 21

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