(2-x)(6-x)(12-x)(20-x)=
问题描述：
(2-x)(6-x)(12-x)(20-x)=
答
=(x²-8x+12)(x²-32x+120)
=x^4-32x³+120x²-8x³+256x²-960x+12x²-384x+1440
=x^4-40x³+388x²-1344x+1440