#### Answer

$p-25s$

#### Work Step by Step

$\bf{\text{Solution Outline:}}$
To simplify the given radical expression, $
(\sqrt[]{p}+5\sqrt{s})(\sqrt[]{p}-5\sqrt{s})
,$ use the special product on multiplying the sum and difference of like terms.
$\bf{\text{Solution Details:}}$
Using the product of the sum and difference of like terms which is given by $(a+b)(a-b)=a^2-b^2,$ the expression above is equivalent
\begin{array}{l}\require{cancel}
(\sqrt[]{p})^2-(5\sqrt{s})^2
\\\\=
p-25s
.\end{array}