The given expression is $3^{-2}$.

To simplify it using only positive exponents, apply the rule of negative exponents:

$a^{-n} = \frac{1}{a^n}$

So:

$3^{-2} = \frac{1}{3^2} = \frac{1}{9}$

Thus, the simplified form is $\frac{1}{9}$.

Let me know if you want additional clarifications!

Expanding knowledge:

1. What is the general rule for simplifying $a^{-n}$?
2. How do negative exponents affect fractional bases?
3. How can negative exponents appear in equations involving variables?
4. What happens when you multiply two terms with negative exponents?
5. How does $3^{-2}$ compare to $(-3)^{-2}$?

Tip: Always simplify negative exponents by rewriting them as fractions to make computations easier!