（5）解：lim(x->∞)[(1+1/x)(2-1/x²)] =[lim(x->∞)(1+1/x)]*[lim(x->∞)(2-1/x²)] =(1+0)*(2-0²) (∵lim(x->∞)(1/x)=0) =1*2 =2。
