Question

if x is 2+sqrt 3 find x2 + 1/x2

Answer 1

(2+√3)^2+1/(2+√3)^2

7+4√3+1/7+4√3

(7+4√3)^2+1/7+4√3

98+56√3/7+4√3

r.f of 7+4√3 is 7-4√3

(98+56√3)(7-4√3)

= ---------------------------

(7+4√3)(7-4√3)

=686+392√3-392√3-672

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49-48

=14