To simplify the expression \( (6^{-1})^2 \), you can use the power of a power property of exponents, which states that \( (a^m)^n = a^{m \cdot n} \).
Applying this rule:
\[ (6^{-1})^2 = 6^{-1 \cdot 2} = 6^{-2} \]
Thus, \( (6^{-1})^2 \) is equivalent to \( 6^{-2} \).