3a+2的绝对值+（2b-1)=0 3a+2=0 2b-1=0 a=-2/3 b=1/2 (3ab-ab)分之(3a-2b+5ab) =(2/3+1/6)分之(4/3-1/4-5/3) =(5/6)分之(-7/12) =-10分之7