Question

帮忙解个不等式方程

－1<=1/x+2<4， 求X范围
我问的是－1<=[（1/x）+2]<4…………

Answer 1

若-1<=1/(x+2)<0
则0<1/[-(x+2)]<=1
所以-(x+2)>=1
x+2<=-1
x<=-3

若0<1/(x+2)<4
则x+2>1/4
x>-7/4

所以x<=-3,x>-7/4

Answer 2

－1<=1/x+2<4
-3<=1/x<2
讨论 当x>0 x>1/2
当x<0 x<=-1/3