a减二分之一的绝对值加b加三分之一的绝对值加c减四分之一的绝对值=0
那么a-1/2=0 b+1/3=0 c-1/4=0
a=1/2 b= -1/3 c=1/4
b-a+c
= -1/3-1/2+1/4
= -10/12+3/12
= -7/12
|a-1/2|+|b+1/3|+|c-1/4|=0
a-1/2=0 b+1/3=0 c-1/4=0(因为绝对值后必须为0结果才能为0)
a=1/2 b= -1/3 c=1/4
b-a+c
= -1/3-1/2+1/4
= -4/12-6/12+3/12
= 7/12