原式=lim(x->∞) [根号下(x²+1) -x]*[根号下(x²+1) ) +x]/[根号下(x²+1) ) +x]=lim(x->∞) [(x²+1) -x²]/[根号下(x²+1) ) +x]=lim(x->∞) 1/[根号下(x²+1) ) +x]=0...