Question

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

Answer 1

x = 2^1/2 + 1

= 2/3

( x + 1/x ) ( X - 1/x )

= x^2 - 1/ x^2.

= ( 2/3 )^2 - 1/ ( 2/3 )^2

= 4/9 - 9/4

= 16 - 81 / 36

= -65 /36