y^-9*y^-3 Fully simplify and write your answer in exponential form with positive exponents only.

To simplify the expression \( y^{-9} \cdot y^{-3} \), we can use the rule of exponents that states \( a^m \cdot a^n = a^{m+n} \).

Applying this rule, we have:

\[
y^{-9} \cdot y^{-3} = y^{-9 + (-3)} = y^{-12}
\]

Next, we want to express our answer in exponential form with positive exponents. To do this, we can rewrite \( y^{-12} \) as:

\[
y^{-12} = \frac{1}{y^{12}}
\]

Thus, the fully simplified expression in exponential form with positive exponents only is:

\[
\frac{1}{y^{12}}
\]