f(x)=(x-1)(x-2)(x-3).(x-2010),则f(2010)的导数=?

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f(x)=(x-1)(x-2)(x-3).(x-2010),则f(2010)的导数=?f(x)=(x-1)(x-2)(x-3).(x-2010),则f(2010)的导数=?f(x)=(x-1)(x-2

f(x)=(x-1)(x-2)(x-3).(x-2010),则f(2010)的导数=?
f(x)=(x-1)(x-2)(x-3).(x-2010),则f(2010)的导数=?

f(x)=(x-1)(x-2)(x-3).(x-2010),则f(2010)的导数=?
令:f(x)=(x-1)(x-2)(x-3).(x-2010)=g(x)(x-2010);其中g(x)=(x-1)(x-2)(x-3).(x-2009);
则:f '(x)=g '(x)(x-2010)+g(x);
所以:f '(2010)=g '(2010)(2010-2010)+g(2010)=0+2009!=2009!;

注意到f(2010)=0
x→2010时,有f'(2010)= lim (f(x)-f(2010))/(x-2010) = lim f(x)/(x-2010)
=lim (x-1)(x-2)(x-3)....(x-2010)/(x-2010)
=lim (x-1)(x-2)(x-3)....(x-2009)
= (2010-1)(2010-2)...(2010-2009)
=2009 * 2008 * ... * 1
=2009!

令g(x)=(x-1)(x-2)……(x-2009)
则f(x)=g(x)*(x-2010)
f(x)导=g(x)导×(x-2010)+g(x)
f(2010)导=g(2010)=2009的阶层

f'(x)=(x-2)(x-3)...(x-2010)+(x-1)(x-3)(x-4)(x-2010)+....(x-1)(x-2)(x-3)..(x-2009)
f'(2010)=(x-1)(x-2)(x-3)(x-4)....(x-2009)=2009*2008*2007*2006*2005...*1=2009!

对f(x)求导,凡是有(x-2010)的F(2010)的倒数为0;
只剩下一项,即f(2010)'=(2010-1)*(2010-2)*.....*(2010-2009)
=2009*2008*2007*.....1
=2009!