解:_________a___0________b__c___由数轴可知 a<0 ,故 |a|=-a b>0 故 |b|=b a+b>0 故 |a+b|=a+b b-c<0 故 |b-c|=-(b-c)=c-b原式=-a+b+a+b+c-b=b+c
lal+lbl+la+bl+lb-cl=-a+b+a+b+c-b=b+c