⑴﹣¼a²﹢3a﹣9⑵3x³-12x²y﹢12xy²

问题描述:

⑴﹣¼a²﹢3a﹣9⑵3x³-12x²y﹢12xy²

(1)-(1/2a-3)²
(2)3x(x²-4xy﹢4y² )
=3x(x-2y)²