The range of the function fx=x-1+x-2,-1≤x≤3 is

Clearly, from the graph, the range is 1,f-1≡1,5.If x<1,fx=-x-1-x-2=2x+3.In this interval, f(x) is decreasing.If  1≤x<2,fx=x-1-x-2=1.In this interval f(x) is constantIf 2≤x≤3,fx=x-1+x-2=2x-3.In this interval f(x) is increasing.∴     max  fx=the  greatest  among  f-1  and  f3=5,        min   fx=f1=1So, range = 1   5