|x-2|+|x+1|>5
case 1: x≤-1
|x-2|+|x+1|>5
-(x-2)-(x+1)>5
-2x+1>5
2x<-4
x<-2
solution for case 1: x<-2
case 2: -1<x<2
|x-2|+|x+1|>5
-(x-2)+(x+1)>5
3>5
False
case 3: x≥2
|x-2|+|x+1|>5
(x-2)+(x+1)>5
2x-1>5
x>3
solution for case 3: x>3
|x-2|+|x+1|>5
case 1 or case 2 or case 3
x<-2 or x>3