x=±1为铅直渐近线；k=lim(x->∞)f(x)/x=lim(x->∞)x³/x(1-x²)=lim(x->∞)1/(1/x²-1)=-1b=lim(x->∞)(x³/(1-x²) +x)=lim(x->∞)(x³+x-x³)/(1-x²)=lim(x->∞)x/(1-x²)=lim(x->∞)(1/x)/(1/x² -1)=0所以斜渐近线为y=-x
