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If X = ( 7 + 4 √ 3 ) , Find the Value of √ X + 1 √ X - Mathematics

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Question

If x = `(7 + 4sqrt(3))`, find the value of

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

Sum

Solution

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

Squaring Both sides we get

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

We will first find out `x + (1)/x`

`x + (1)/x = (7 + 4sqrt(3)) + (1)/((7 + 4sqrt(3))`

= `((7 + 4sqrt(3)^2 + 1))/((7 + 4sqrt(3))`

= `(49 + 48 + 56sqrt(3) + 1)/((7 + 4sqrt(3))`

= `(98 + 56sqrt(3))/((7 + 4sqrt(3))`

= `(14(7 + 4sqrt(3)))/((7 + 4sqrt(3))` 

= 14

substitutingin (1)

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

= 14 + 2

= 16

∴ `sqrt(x) + (1)/sqrt(x)` = 4

shaalaa.com
Simplifying an Expression by Rationalization of the Denominator
  Is there an error in this question or solution?
Chapter 1: Irrational Numbers - Exercise 1.3

APPEARS IN

Frank Mathematics [English] Class 9 ICSE
Chapter 1 Irrational Numbers
Exercise 1.3 | Q 7.1
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