F.2數學題1條 (10分!!!!!)

(a-2b)²+(2a-b)(2b-a)

=(a²-4ab+4b²)+(4ab-2a²-2b²+ab)

=a²-4ab+4b²+4ab-2a²-2b²+ab

=-a²+2b²+ab

=a²-2b²-ab --->le步唔知要唔要
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應該你correct

2008-02-20 18:19:22 補充：
應該係correct

(a - 2b) [(a -2b) - (2a -b)]
= (a - 2b) (a- 2a -2b + b)
= (a - 2b) (-a - b)
= (a+b) (2b - a)