Here, we want to solve an expansion
To get this, we simply multiply the terms in the first bracket with the terms in the second, before we proceed to collect like terms
We have this as follows;
[tex]\begin{gathered} (s+5)(s-5)\text{ = s(s-5)+5(s-5)} \\ =s^2-5s+5s-25 \\ =s^2-25 \end{gathered}[/tex]