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महाराष्ट्र राज्य शिक्षण मंडळएचएससी विज्ञान (सामान्य) इयत्ता ११ वी

Express the following in the form of a + ib, a, b ∈ R i = −1. State the values of a and b: ii(-5+2-4)+(1--9)+(2+3i)(2-3i)

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प्रश्न

Express the following in the form of a + ib, a, b ∈ R i = `sqrt(−1)`. State the values of a and b:

`(- sqrt(5) + 2sqrt(-4)) + (1 -sqrt(-9)) + (2 + 3"i")(2 - 3"i")`

बेरीज
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उत्तर

`(- sqrt(5) + 2sqrt(-4)) + (1 -sqrt(-9)) + (2 + 3"i")(2 - 3"i")`

= `(- sqrt(5) + 2sqrt(4).sqrt(-1)) + (1 -sqrt(9).sqrt(-1)) + 2^2 - 9"i"^2`

= `(- sqrt(5) + 2(2)"i") + (1 - 3"i") + 4 - 9"i"^2`

= `-sqrt(5) + 4"i" + 1 - 3"i" + 4 - 9(-1)`   ...[∵ i2 = – 1] 

= `-sqrt5+"i"+1+4+9`

= `-sqrt5+"i"+14`

= `(14 -sqrt(5)) + "i"`

This is of the form a + bi, where a = `14-sqrt(5)` and b = 1.

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पाठ 1: Complex Numbers - Exercise 1.1 [पृष्ठ ६]

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