知有理数a、b满足|2a-3b-5|+（2a+3b-3）^2=0 求 -2ab^2的值
满足2a-3b-5= 0 2a+3b-3 = 0
相加4a = 8a= 2
3b = 2a-5= -1
b = -1/3
-2ab^2
=-2x2 x1/9
=- 9分之4