3(x-y)^2-12(x-y)^2+9帮帮忙啊啊.我很急^O^
问题描述:
3(x-y)^2-12(x-y)^2+9帮帮忙啊啊.我很急^O^
答
3(x-y)^2-12(x-y)^2+9
=-9(x-y)²+9
=-9[(x-y)²-1]
=-9(x-y+1)(x-y-1)