已知函数f(x)=1(x>=0) f(x)=-1(x

题目

已知函数f(x)=1(x>=0) f(x)=-1(x

答案

若x+2>=0,x>=-2
则f(x+2)=1
则x+(x+2)*1<=5
2x+2<=5
x<=3/2
所以-2<=x<=3/2
若x+2<0,x<-2
则f(x+2)=-1
则x+(x+2)*(-1)<=5
2x-2<=5
x<=7/2
所以x<-2
综上
x≤3/2