To simplify \( 13^{-5} \cdot 13^{-11} \) using the properties of exponents, we apply the rule that states \( a^m \cdot a^n = a^{m+n} \).
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First, add the exponents: \[ -5 + (-11) = -16 \] So, we have: \[ 13^{-5} \cdot 13^{-11} = 13^{-16} \]
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Next, to express this with only positive exponents, we recall that \( a^{-n} = \frac{1}{a^n} \): \[ 13^{-16} = \frac{1}{13^{16}} \]
Thus, the equivalent expression to \( 13^{-5} \cdot 13^{-11} \) expressed with positive exponents is: \[ \frac{1}{13^{16}} \]
So the correct answer is: \[ \text{1/13}^{{16}} \]