Answer :

To simplify the expression and rewrite it in the form [tex]\(5^n\)[/tex], follow these steps:

1. Identify the base and exponents: The base in both terms is 5, and the exponents are -8 and -10.

2. Use the properties of exponents: According to the properties of exponents, specifically the multiplication rule for powers of the same base, we have
[tex]\[ a^m \cdot a^n = a^{m+n} \][/tex]
Here, [tex]\(a = 5\)[/tex], [tex]\(m = -8\)[/tex], and [tex]\(n = -10\)[/tex].

3. Add the exponents: Combine the exponents from the terms by adding them together:
[tex]\[ -8 + (-10) = -8 - 10 = -18 \][/tex]

4. Rewrite the expression: Now that we have the exponent sum, rewrite the expression in the simplified form
[tex]\[ 5^{-18} \][/tex]

Hence, the simplified expression is
[tex]\[ \boxed{5^{-18}} \][/tex]