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If x = √2 + 1, find x + 1/x. - Mathematics

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Question

If `x = sqrt(2) + 1`, find `x + 1/x`.

Sum
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Solution

Given: `x = sqrt(2) + 1`

Step-wise calculation:

1. Find `1/x`:

`1/x = 1/(sqrt(2) + 1)`

= `1/(sqrt(2) + 1) xx (sqrt(2) - 1)/(sqrt(2) - 1)`

= `(sqrt(2) - 1)/(2 - 1)`

= `sqrt(2) - 1`

2. Find `x + 1/x`:

`x + 1/x = (sqrt(2) + 1) + (sqrt(2) - 1)`

\[ x + \frac{1}{x} = 2 \sqrt{2} \]

Thus, the value of `x + 1/x` is `2sqrt(2)`.

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Chapter 1: Rational and Irrational Numbers - Exercise 1E [Page 32]

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Nootan Mathematics [English] Class 9 ICSE
Chapter 1 Rational and Irrational Numbers
Exercise 1E | Q 6. (ii) | Page 32
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