3^7x3^-9

To solve the expression 3^7 × 3^-9, we can simplify it using the properties of exponents.

First, we can combine the two terms with the same base of 3 by adding their exponents:
3^7 × 3^-9 = 3^(7 + -9)

Next, we simplify the resulting exponent:
= 3^(-2)

Since the base is 3 and the exponent is -2, we can write the expression as the reciprocal of 3^2:
= 1 / 3^2

Finally, we evaluate 3^2:
= 1 / 9

Therefore, 3^7 × 3^-9 equals 1/9.