Simplify. Express your answer using a single exponent. (7h^9)²

To simplify ((7h^9)²), apply the power of a power rule, which states that ((a^m)² = a^{2m}), and also remember to square the coefficient.

1. Square the coefficient: (7² = 49).
2. Apply the power to the variable: ((h^9)² = h^{9 cdot 2} = h^{18}).

Putting it all together, we have:

[

(7h^9)² = 49h^{18}

]

Your final answer is (49h^{18}).