a^6• a^-10

To simplify the expression \( a^6 \cdot a^{-10} \), you can use the property of exponents that states:

\[ a^m \cdot a^n = a^{m+n} \]

Applying this property here:

\[ a^6 \cdot a^{-10} = a^{6 + (-10)} = a^{-4} \]

So, the simplified form of the expression is:

\[ a^{-4} \]

If desired, you can also express this in a different form:

\[ a^{-4} = \frac{1}{a^4} \]

Thus, \( a^6 \cdot a^{-10} = a^{-4} = \frac{1}{a^4} \).