已知 |a+1|+(b-2)²=0 ,求 2a²-[8ab+1/2(ab-4a²)]-1/2ab 的值.

已知 |a+1|+(b-2)²=0 ,求 2a²-[8ab+1/2(ab-4a²)]-1/2ab 的值.
已知 |a+1|+(b-2)²=0 ,求 2a²-[8ab+1/2(ab-4a²)]-1/2ab 的值.

已知 |a+1|+(b-2)²=0 ,求 2a²-[8ab+1/2(ab-4a²)]-1/2ab 的值.
|a+1|+(b-2)²=0
所以a+1=b-2=0
a=-1,b=2
所以原式=2a²-8ab-1/2ab+2a²-1/2ab
=4a²-9ab
=4+18
=22

|a+1|+(b-2)²=0
所以a+1=0,b-2=0
所以a=-1,b=2
所以2a²-[8ab+1/2(ab-4a²)]-1/2ab=2-[-16-3]+1=3+16+3=22