Answer:
s²+2s-80
Step-by-step explanation:
First (first in each parentheses)
Outside (the two terms on the outside of the expression)
Inside (the two terms in the inside of the expression)
Last (last in each parentheses)
An example:
(a+b)(c+d)=ac+ad+bc+bd
Therefore...
(s+10)(s-8)=(s)(s)+(s)(-8)+(10)(s)+(10)(-8)=s²-8s+10s-80=s²+2s-80
