Chapter 5 - Section 5.3 - Special Products - Exercise Set - Page 367: 42

$4-s^{10}$

Using $(a+b)(a-b)=a^2-b^2$ or the special product of the sum and difference of like terms, the product of the given expression, $ (2-s^5)(2+s^5) ,$ is \begin{array}{l}\require{cancel} 2(2)-s^5(s^5) \\\\= 4-s^{10} .\end{array}