令a=2014
2012=a-2
2013=a-1
a^3-(a-2)^3-6a^2+12(a-1)
立方差公式
=(a-a+2)[a^2+a(a-2)+(a-2)^2]-(6a^2-12a+12)
=2(a^2+a^2-2a+a^2-4a+4)-6(a^2-2a+2)
=2(3a^2-6a+4)-6a^2+12a-12
=6a^2-12a+8-6a^2+12a-12
=-4
令a=2014
2012=a-2
2013=a-1
a^3-(a-2)^3-6a^2+12(a-1)
立方差公式
=(a-a+2)[a^2+a(a-2)+(a-2)^2]-(6a^2-12a+12)
=2(a^2+a^2-2a+a^2-4a+4)-6(a^2-2a+2)
=2(3a^2-6a+4)-6a^2+12a-12
=6a^2-12a+8-6a^2+12a-12
=-4