8个常用泰勒公式:

sin ⁡ x = x − 1 6 x 3 + O ( x 3 ) arcsin ⁡ x = x + 1 6 x 3 + O ( x 3 ) \sin x=x-\frac{1}{6} x^{3}+O\left(x^{3}\right) \quad \arcsin x=x+\frac{1}{6} x^{3}+O\left(x^{3}\right) sinx=x−61​x3+O(x3)arcsinx=x+61​x3+O(x3)

cos ⁡ x = 1 − 1 2 x 2 + x 4 4 ! + 0 ( x 4 ) ln ⁡ ( 1 + x ) = x − 1 2 x 2 + 1 3 x 3 + O ( x 3 ) \cos x=1-\frac{1}{2} x^{2}+\frac{x^{4}}{4 !}+0\left(x^{4}\right) \quad \ln (1+x)=x-\frac{1}{2} x^{2}+\frac{1}{3} x^{3}+O(x^{3}) cosx=1−21​x2+4!x4​+0(x4)ln(1+x)=x−21​x2+31​x3+O(x3)

tan ⁡ x = x + 1 3 x 3 + O ( x 3 ) arctan ⁡ x = x − 1 3 x 3 + O ( x 3 ) \tan x=x+\frac{1}{3} x^{3}+O( x^{3}) \quad \arctan x=x-\frac{1}{3} x^{3}+O\left(x^{3}\right) tanx=x+31​x3+O(x3)arctanx=x−31​x3+O(x3)

e x = 1 + x + 1 2 x 2 + 1 6 x 3 + 0 ( x 3 ) ( 1 + x ) a = 1 + a x + + a ( a − 1 ) 2 ! x 2 + O ( x 2 ) e^{x}=1+x+\frac{1}{2} x^{2}+\frac{1}{6} x^{3}+0\left(x^{3}\right) \quad(1+x)^{a}=1+a x++\frac{a(a-1)}{2 !} x^{2}+O\left(x^{2}\right) ex=1+x+21​x2+61​x3+0(x3)(1+x)a=1+ax++2!a(a−1)​x2+O(x2) 泰勒公式是等号而不是等价，这就使所有函数转化为幂函数，在利用高阶无穷小被低阶吸收的原理，可以秒杀大部分极限题。