Question

已知(2a-1)²+丨b+1丨=0.求2(3a²b-ab²)-(2ab²+2a²b)的值

急啊...

Answer 1

(2a-1)²+丨b+1丨=0.
(2a-1)²=0,丨b+1丨=0.
a=1/2,b=-1

2(3a²b-ab²)-(2ab²+2a²b)
=6a²b-2ab²-2ab²-2a²b
=6a²b-2a²b-2ab²-2ab²
=4a²b-4ab²
=4ab(a-b)
=4*1/2*(-1)*[1/2-(-1)]
=-2*3/2
=-3

Answer 2

因为(2a-1)²≥0，丨b+1丨≥0
所以2a-1=0，b+1=0
解得a=1/2，b=-1
代数式2(3a²b-ab²)-(2ab²+2a²b)
=2ab(3a-b)-2ab(b+a)
=2ab(3a-b-b-a)
=-1×3
=-3
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