exp(tan(x))-exp(sin(x))
=exp(sinx)[exp(tan(x)-sin(x))-1],(x->0)
=exp(tan(x)-sin(x))-1,(exp(x)-1 ~ x,x->0)
=tan(x)-sin(x)
=[sinx(1-cosx)]/cosx,(x->0)
=sinx(1-cosx)
所以n=3
exp(tan(x))-exp(sin(x))
=exp(sinx)[exp(tan(x)-sin(x))-1],(x->0)
=exp(tan(x)-sin(x))-1,(exp(x)-1 ~ x,x->0)
=tan(x)-sin(x)
=[sinx(1-cosx)]/cosx,(x->0)
=sinx(1-cosx)
所以n=3