The document provides examples of determining the domain intervals where the range of functions is positive or negative based on their graphs. For a function f(x)=x^2-2x-3, the range is positive when x<-1 or x>3, and negative when -1<x<3. For -2x^2+5x+3, the range is positive when -0.5<x<3 and negative when x<-0.5 or x>3. Finally, for x^2-2x-5, the range is positive when x<-5 or x>-3, and negative when -5<x<-3.