解:(1)原式=﹣3×=﹣;
(2)原式=4x4﹣27x4=﹣23x4;
(3)原式=6x2+4x﹣3x﹣2=6x2+x﹣2;
(4)原式=2ab﹣3c;
(5)原式=﹣3y×3xy=﹣9xy2;
(6)原式=20012﹣(2001+1)(2001﹣1)=20012﹣20012+1=1;
(7)原式=(x2﹣2xy+y2)(y2﹣4x2)=x2y2﹣4x4﹣2xy3+8x3y+y4﹣4x2y2=﹣3x2y2﹣4x4﹣2xy3+8x3y+y4;
(8)原式=(+3y+﹣3y)(+3y﹣+3y)=a×6y=6ay.
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