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If M = 1/ 3 - 2sqrt2 and N = 1/ 3 + 2sqrt2 Find - Mathematics

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Question

If m = `1/[ 3 - 2sqrt2 ] and n = 1/[ 3 + 2sqrt2 ],` find m2

Sum

Solution

m = `1/[ 3 - 2sqrt2 ]`

m = `1/[ 3 - 2sqrt2 ] xx [ 3 + 2sqrt2 ]/[ 3 + 2sqrt2 ]`

m = `[ 3 + 2sqrt2 ]/[ (3)^2 - (2sqrt2)^2 ]`

m = `[ 3 + 2sqrt2 ]/[ 9 - 8 ]`

m = 3 +2√2

⇒ m2 = ( 3 + 2√2)2

           = (3)2 + 2 x 3 x 2√2 + (2√2)2

           = 9 + 12√2  + 8

           = 17 + 12√2

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Rationalisation of Surds
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Chapter 1: Rational and Irrational Numbers - Exercise 1 (C) [Page 22]

APPEARS IN

Selina Concise Mathematics [English] Class 9 ICSE
Chapter 1 Rational and Irrational Numbers
Exercise 1 (C) | Q 7.1 | Page 22
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