Question: Simplify $x^{-7}$. Write your answer using only positive exponents.
1. **State the problem:** Simplify the expression $x^{-7}$ so that it contains only positive exponents.
2. **Recall the rule for negative exponents:** For any nonzero number $a$ and integer $n$, $a^{-n} = \frac{1}{a^n}$.
3. **Apply the rule:**
$$x^{-7} = \frac{1}{x^7}$$
4. **Final answer:** The expression with only positive exponents is:
$$\boxed{\frac{1}{x^7}}$$
This means that a negative exponent indicates the reciprocal of the base raised to the positive exponent.