what would this be using a positive exponent?

1 / 9^4 and 1 / 6^3
This is because in order to make a negative exponent into a postive exponent, you need to make it into a fraction, 1 as the top number, and the negative exponent as a postive one.
For example, 6^-3 becomes 1 / 6^3.
I hope I helped.