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Expand: (3 – sqrt(8))^2 - Mathematics

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Question

Expand:

`(3 - sqrt(8))^2`

Sum
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Solution

Let’s expand:

`(3 - sqrt(8))^2`

Use the identity:

(a – b)2 = a2 – 2ab + b2

Let:

  • a = 3
  • `b = sqrt(8) = 2sqrt(2)`

Now expand:

= `3^2 - 2(3)(2sqrt(2)) + (2sqrt(2))^2`

= `9 - 12sqrt(2) + 4 xx 2`

= `9 - 12sqrt(2) + 8`

= `17 - 12sqrt(2)`

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Chapter 1: Rational and Irrational Numbers - MISCELLANEOUS EXERCISE [Page 17]

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B Nirmala Shastry Mathematics [English] Class 9 ICSE
Chapter 1 Rational and Irrational Numbers
MISCELLANEOUS EXERCISE | Q 2. (ii) | Page 17
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