泰勒公式是将一个在x=x0处具有n阶导数的函数f(x)利用关于(x-x0)的n次多项式来逼近函数的方法。
![](https://gss1.bdstatic.com/9vo3dSag_xI4khGkpoWK1HF6hhy/baike/s%3D561/sign=143f6442fadeb48fff69a1d8c11e3aef/a686c9177f3e670920f8bbdc32c79f3df8dc551d.jpg)
其中,
表示f(x)的n阶导数,等号后的多项式称为函数f(x)在x0处的泰勒展开式,剩余的Rn(x)是泰勒公式的余项,是(x-x0)n的高阶无穷小。
![](https://gss1.bdstatic.com/-vo3dSag_xI4khGkpoWK1HF6hhy/baike/s%3D48/sign=cdaffac6023b5bb5bad721f637d3f4ac/a71ea8d3fd1f41347291fe13241f95cad1c85e3d.jpg)
余项
泰勒公式的余项Rn(x)可以写成以下几种不同的形式:
1、佩亚诺(Peano)余项:
![](https://gss2.bdstatic.com/-fo3dSag_xI4khGkpoWK1HF6hhy/baike/s%3D140/sign=aaeb400308e939015202893a4bec54f9/cdbf6c81800a19d86a0c7c263afa828ba61e4682.jpg)
这里只需要n阶导数存在
2、施勒米尔希-罗什(Schlomilch-Roche)余项:
![](https://gss0.bdstatic.com/-4o3dSag_xI4khGkpoWK1HF6hhy/baike/s%3D375/sign=f7ad04f91cce36d3a60485370ff33a24/7aec54e736d12f2e1520564346c2d562853568e8.jpg)
3、拉格朗日(Lagrange)余项:
![](https://gss2.bdstatic.com/9fo3dSag_xI4khGkpoWK1HF6hhy/baike/s%3D289/sign=28b4e36082d4b31cf43c93b3bed6276f/54fbb2fb43166d222d13edb74f2309f79052d2a9.jpg)
其中θ∈(0,1)。
4、柯西(Cauchy)余项:
![](https://gss0.bdstatic.com/-4o3dSag_xI4khGkpoWK1HF6hhy/baike/s%3D345/sign=8e449a3f18dfa9ecf92e501357d1f754/d62a6059252dd42a54a3f9880a3b5bb5c9eab86f.jpg)
其中θ∈(0,1)。
5、积分余项:
![](https://gss1.bdstatic.com/9vo3dSag_xI4khGkpoWK1HF6hhy/baike/s%3D260/sign=72053e9fd6c451daf2f60bed86ff52a5/4b90f603738da97750c220eabb51f8198718e306.jpg)
带佩亚诺余项
![](https://gss0.bdstatic.com/94o3dSag_xI4khGkpoWK1HF6hhy/baike/s%3D240/sign=af5105143cfae6cd08b4ac653fb30f9e/4bed2e738bd4b31cbf7b70988ed6277f9e2ff84a.jpg)
![](https://gss1.bdstatic.com/-vo3dSag_xI4khGkpoWK1HF6hhy/baike/s%3D235/sign=aa5a1804763e6709ba0042fc0ec69fb8/7a899e510fb30f244f7b0820c195d143ad4b032b.jpg)
![](https://gss0.bdstatic.com/-4o3dSag_xI4khGkpoWK1HF6hhy/baike/s%3D216/sign=010037de72899e517c8e3d1574a6d990/f9198618367adab47e17ff6082d4b31c8601e4ca.jpg)
![](https://gss1.bdstatic.com/-vo3dSag_xI4khGkpoWK1HF6hhy/baike/s%3D407/sign=299b9a25f91f3a295ec8d4ceae27bce3/d0c8a786c9177f3ec2c6c7f679cf3bc79e3d565e.jpg)
![](https://gss3.bdstatic.com/7Po3dSag_xI4khGkpoWK1HF6hhy/baike/s%3D217/sign=6137b9730533874498c5287d660fd937/b3b7d0a20cf431ad5cfca41a4236acaf2edd98e3.jpg)
![](https://gss2.bdstatic.com/9fo3dSag_xI4khGkpoWK1HF6hhy/baike/s%3D208/sign=f90c39d7be4543a9f11bfdcc26178a7b/03087bf40ad162d9b8c6853f18dfa9ec8a13cded.jpg)