求导数函数f(x)=x(x
f(x)=x(x-1)(x-2)(x-3)(x-4)(x-5) 在0处的导数值如何求？
lnf(x)=lnx+ln(x-1)+ln(x-2)+ln(x-3)+ln(x-4)+ln(x-5) 两边同时其导数 f'(x)/f(x)=1/x+1/(x-1)+……+1/(x-5) --->f'(x)=f(x)[1/x+1/(x-1)+……+1/(x-5)] =(x-1)(x-2)(x-3)(x-4)(x-5) +x(x-2)(x-3)(x-4)(x-5) +x………………………… +x(x-1)(x-2)(x-3)(x-4) 所以f'(0)=(-1)(-2)(-3)(-4)(-5)+0+0+0+0+0+0=-120.