(n^9)^-2 ​(Simplify your answer. Use positive exponents​ only.)

To simplify the expression ((n^9)^-2), we can apply the property of exponents which states that (a^m)^n = a^(m*n).

Using this property, we have:
((n^9)^-2) = n^(9*-2)
= n^(-18)

Therefore, the simplified expression is n^(-18).