Question

已知丨a-2丨+(b+1)²=0,求5ab²-[2a²b-(4ab²-2a²b)]的值

Answer 1

丨a-2丨+(b+1)²=0
a-2=0, b+1=0
a=2, b=-1
5ab²-[2a²b-(4ab²-2a²b)]
=5ab²-(2a²b-4ab²+2a²b)
=5ab²-4a²b+4ab²
=9ab²-4a²b

Answer 2

已知丨a-2丨+(b+1)²=0,求5ab²-[2a²b-(4ab²-2a²b)]的值
解：∵丨a-2丨≥0
(b+1)² ≥0
∴a-2=0, b+1=0
∴a=2,b=-1
∴5ab²-[2a²b-(4ab²-2a²b)]
= 5ab²-(2a²b-4ab²+2a²b)
=5ab²-(4a²b-4ab²)
=5ab²-4a²b+4ab²
=9ab²-4a²b
=9×2×(-1)2-4×22×(-1)
=34