Simplify the Radical Expression (5^-8)(5^-10)

$(5^{- 8}) (5^{- 10})$

Multiply $5^{- 8}$ by $5^{- 10}$ by adding the exponents.

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$5^{- 8 - 10}$

Subtract $10$ from $- 8$ .

$5^{- 18}$

Rewrite the expression using the negative exponent rule $b^{- n} = \frac{1}{b^{n}}$ .

$\frac{1}{5^{18}}$

Raise $5$ to the power of $18$ .

$\frac{1}{3814697265625}$