5绝对值: -aa<0 (a≥0) 运算性质:mb=ab; b 6 a-b≤a±b≤a+b 绝对值不等式: x≤a(a>0)~-a≤x≤; x≥a(a>0)x≥a或x≤-m; 上页5.绝对值:    −   = 0 0 a a a a a ( a  0) 运算性质: ab = a b; ; b a b a = a − b  a  b  a + b. x  a (a  0) − a  x  a; x  a (a  0) x  a 或 x  −a; 绝对值不等式: