How do u solve 20s<-640

Given the graph below state whether or not the relation is a function, and give the domain and range.

Find the value of the variable and the length of each secant segment.

Marquise has 200 meters of fencing to build a rectangular garden. the garden's area (in square meters) as a function of the garden's width w w (in meters) is modeled by: a ( w ) = − w 2 + 1 0 0 w a(w)=−w 2 +100w what side width will produce the maximum garden area? meters