设x→0时,etanx-ex与xn是同阶无穷小,则n为(  )A.1B.2C.3D.

设x→0时,etanx-ex与xn是同阶无穷小,则n为(  )A.1B.2C.3D.4
2025-03-23 07:53:12
推荐回答(1个)
回答1:


tanx=x+
1
3
x3+o(x3)

  etanx-x-1~tanx-x
etanx?exex(etanx?x?1)=
1
3
x3+o(x3)

∴etanx-ex和x3是同阶非等价无穷小
∴n=3
故选:C.