Question

(3^(n)+3^(-n))/(9^(2n)+1)

Answer 1

(3^(n)+3^(-n))/(9^(2n)+1)=

=(3^(n)+13^n)/(9^(2n)+1)=

(9^(2n)+1)/((9^(2n)+1)*(3^(n))=1(3^(n))=3^(-n)