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If X = 2 3 + √ 7 ,Then (X−3)2 = - Mathematics

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Question

If x = \[\frac{2}{3 + \sqrt{7}}\],then (x−3)2 =

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Solution

Given that: `x=2/(3+sqrt7)`

We know that rationalization factor for `3+sqrt7` is .`3-sqrt7` We will multiply numerator and denominator of the given expression `2/(3+sqrt7)` by `3 - sqrt7`, to get

`x = 2/(3+sqrt7) xx (3-sqrt7)/ (3-sqrt7)`

`= (2(3-sqrt7))/((3)^2 - (sqrt7)^2)`

`=  (2(3-sqrt7))/(9-7) `

`= 3 - sqrt7`

Therefore,

`x-3 =-sqrt7`

On squaring both sides, we get

 `(x-3)^2 = 7`

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Chapter 3: Rationalisation - Exercise 3.4 [Page 17]

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RD Sharma Mathematics [English] Class 9
Chapter 3 Rationalisation
Exercise 3.4 | Q 10 | Page 17

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