To simplify the expression \( r^{-4}p^{-8} \), we can rewrite it using positive exponents:
\[ r^{-4} = \frac{1}{r^4} \] \[ p^{-8} = \frac{1}{p^8} \]
Thus, the expression can be rewritten as:
\[ r^{-4}p^{-8} = \frac{1}{r^4} \cdot \frac{1}{p^8} = \frac{1}{r^4 p^8} \]
So the simplified form of the expression is:
the fraction with numerator 1 and denominator \( r^4 p^8 \).