已知3的8n次方=2,求9的-n-1次方乘27的-2n次方

已知3的8n次方=2,求9的-n-1次方乘27的-2n次方

3^(8n)=2
9^(-n-1)×27^(-2n)
=3^[2(-n-1)]×3^[3(-2n)]
=3^[2(-n-1)+3(-2n)]
=3^(-8n-2)
=1/3^(8n+2)
=1/[3^(8n)×3^2]
=1/(2×9)
=1/18