a＜b,a＜c,b=c,當(dāng)a≥2時(shí),原式=a-2-2=a-4
當(dāng)a＜2時(shí),原式=2-a-2=﹣a???????????????????a-b??0??????a??b???????a-c??0??????a??c??????????????????????и??κ?????????????????????????????????????a???С????????????|a-2|?????????????a-2????2-a???????b=c??????|b-c-2|=|-2|=2??????д????????????????~~~~???????????????????a-1=b-c??0....??????????a-1??0????a??1??????a-2??0?????|a-2|????????2-a???????b-c=a-1??????|b-c-2|????????|a-1-2|=|a-3|??a-3??0???????3-a????????????????????????κ?????+a-3???????￡???=2-a+a-3=??1??????????-a+b-c????????????????????????????????????????????????????????????????????????????~~~????????д???????-a+b-c?????????????????????????????????????a-2??0??????|a-2|=2-a??????|b-c-2|???b-c?????a-1???????????????????????-1a-2?????0????????????a-1=b-c??0a-1??0a??1??????a-2??0