To simplify 9^-3 × 9^9 in exponential form, we can use the rule that states when multiplying two numbers with the same base, we add their exponents.
Therefore, 9^-3 × 9^9 can be written as 9^(-3+9).
Simplifying the exponents, we get 9^(6).
Thus, 9^-3 × 9^9 can be written in exponential form as 9^6.