已知f(x)=|x+1|+|x-1|,不等式f(x)

题目

已知f(x)=|x+1|+|x-1|,不等式f(x)

答案

1、①当x＜ - 1时,x+1＜0,x-1＜1∴f(x)=-x-1+1-x=-2x＜4x＞-2即-2＜x＜-1②当-1≤x≤1时,x+1≥0,x-1≤0∴f(x)=x+1+1-x=2＜4∴当-1≤x≤1时都满足③当x＞1时,x+1＞0,x-1＞0∴f(x)=x+1+x-1=2x＜41＜x＜2综上,-2＜x＜2...