若|a-b+3|+|2a+b|=0,先化简再求值.2a3b(2ab+1)-a2(-2ab)2.

问题描述:

若|a-b+3|+|2a+b|=0,先化简再求值.2a3b(2ab+1)-a2(-2ab)2

原式=4a4b2+2a3b-4a4b2=2a3b,
∵|a-b+3|+|2a+b|=0,

a−b+3=0
2a+b=0

解得:a=-1,b=2,
代入得:原式=-4.