If x = 2 + \sqrt3 , then x^2 +1/x^2 is equal to

SSC CHSL Model Paper 5

Question : 43 of 100

Marks: +1, -0

x = 2 + √3

, then

x^2 +1/x^2

is equal to

Solution:

x = 2 + √3

1/x = 1/{ 2 + √3 }×{ 2 - √3 }/{ 2 - √3 }=2-√3

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

=(2 + √3 + 2 - √3 )^2 - 2

= 1 6 -2 = 1 4

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