To simplify \( y^{-2} \cdot y^{-6} \), we can use the property of exponents that states when you multiply two powers with the same base, you add the exponents:
\[ y^{-2} \cdot y^{-6} = y^{-2 + (-6)} = y^{-8} \]
Now, to express this in exponential form with positive exponents only, we can rewrite \( y^{-8} \) using the property that \( a^{-n} = \frac{1}{a^n} \):
\[ y^{-8} = \frac{1}{y^8} \]
Thus, the fully simplified expression is:
\[ \frac{1}{y^8} \]