|3a-1|+(2b+1)的平方=0
|3a-1|=0
(2b+1)的平方=0
3a-1=0
a=1/3
2b+1=0
b=-1/2
2a平方+3b的平方/a-b
=[2(1/3)^2+3(-1/2)^2]/[1/3-(-1/2)]
=(2/9-3/4)/(1/3+1/2)
=(-19/36)/(5/6)
=-19/30