求极限计算题 1、x→0lim(e^tanx-e^x)/(sinx-xcosx) 2、x→无穷lim(1-2/x+1/x^2)^x 谢谢


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简单计算一下即可,答首肢芹历案如者首世图所示


  哪森1、lim(x→0)[(e^tanx)-(e^x)]/(sinx-xcosx)
  = lim(x→0)(e^x)*lim(x→0)[e^(tanx-x)-1]/(sinx-xcosx)
  = 1*lim(x→0)(tanx-x)/(sinx-xcosx) (0/0)
  = lim(x→0)[(secx)^2 - 1]/(xsinx)
  = lim(x→0)[(1+cosx)/(cosx)^2]*lim(x→0)(1-cosx)/(x^2)
  = ……

  2、lim(x→inf.)(1 - 2/x + 1/x^2)^x
  = lim(t→0)(1 - 2t + t^2)^(1/t)
  = e^lim(t→0)ln(1 - 2t + t^2)/t,

   lim(t→0)ln(1 - 2t + t^2)/t (0/0)
  = lim(t→0)(-2 +2t)/(1 - 2t + t^2)
  = -2,

   lim(x→inf.)(1 - 2/卖李x + 1/中缓迟x^2)^x
  = e^(-2)。