A set of weights includes a`20`lb barbell and`6`pairs of weight plates. Each pair of plates weighs `30` lb. If`x`pairs of plates are added to the barbell, the total weight of the barbell and plates in pounds can be represented by `f(x)=30x+20.` What is the range and domain, is it constant or discrete?
clearly discrete, since there are no fractional plates.
as for the domain, they told you how many pairs of weight plates there are, right? So any discrete value that is within that specification will work. (assume there are no negative plates ...)