lnf(x)=ln(x-1)+ln(x-2)+ln(x-3)+ln(x-4)
两边求导
∴f ' (x)/f(x)=1/(x-1)+1/(x-2)+1/(x-3)+1/(x-4)
∴f ' (x)=f(x)*[1/(x-1)+1/(x-2)+1/(x-3)+1/(x-4)]
=(x-2)(x-3)(x-4)+(x-1)(x-3)(x-4)+(x-1)(x-2)(x-4)+(x-1)(x-2)(x-3)
∴f ' (1)=-1*(-2)*(-3)+0+0+0=-6
多个多项式或者单项式连乘,均用对数法,两边取对数,后求导。
这事情,哥劝你自己问老师,毕竟我帮不了你 去高考