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Expand: (4sqrt(5) + 3sqrt(7))^2 - Mathematics

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Question

Expand:

`(4sqrt(5) + 3sqrt(7))^2`

Sum
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Solution

Let’s expand:

`(4sqrt(5) + 3sqrt(7))^2`

Use the identity:

(a + b)2 = a2 + 2ab + b2

Let:

  • `a = 4sqrt(5)`
  • `b = 3sqrt(7)`

Now compute each term:

  • `a^2 = (4sqrt(5))^2 = 16 xx 5 = 80`
  • `2ab = 2 xx 4sqrt(5) xx 3sqrt(7) = 24sqrt(35)`
  • `b^2 = (3sqrt(7))^2 = 9 xx 7 = 63`

Now add them:

`(4sqrt(5) + 3sqrt(7))^2`

= `80 + 24sqrt(35) + 63`

= `143 + 24sqrt(35)`

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Chapter 1: Rational and Irrational Numbers - EXERCISE 1C [Page 15]

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B Nirmala Shastry Mathematics [English] Class 9 ICSE
Chapter 1 Rational and Irrational Numbers
EXERCISE 1C | Q 5. (iv) | Page 15
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