令s1=x-1-x(x-1)+x(x-1)^2-x(x-1)^3+……-x(x-1)^2011+x(x-1)^2012(1)两边乘(x-1)得（x-1)s1=(x-1)^2-x(x-1)^2+x(x-1)^3-……+x(x-1)^2011-x(x-1)^2012+x(x-1)^2013(2)(1)+(2)得s1+(x-1)s1=x-1-x(x-1)+(x-1)^2+x(x-1...