lnf﹙x﹚=∫f﹙t﹚dt,两边求导得到f'(x)/f(x)=f(x)即df/dx=f²df/f²=dx,两边积分∫df/f²=∫dx+C,得到-1/f=x+C,即f(x)=-1/(x+C),将x=1代入求的C=-2所以f(x)=-1/(x-2)
lnf﹙x﹚=∫f﹙t﹚dtf(x)=[lnf(x)]'=f'(x)/f(x)df(x)/f^2(x)=dx-1/f(x)=x+Cf﹙1﹚=1, -1=1+C, C=-2f(x)=1/(2-x)