已知当X趋近于0时,x^2ln(1+x^2)是sin^n(x)的高阶无穷小,sin^n(x)又是1-cosx的高阶无穷小,求正整数n

问题描述:

已知当X趋近于0时,x^2ln(1+x^2)是sin^n(x)的高阶无穷小,sin^n(x)又是1-cosx的高阶无穷小,求正整数n

x^2ln(1+x^2)等价于x^4
1-cosx等价于x^2/2
所以
x^2ln(1+x^2)是sin^n(x)的高阶无穷小,sin^n(x)又是1-cosx的高阶无穷小

sin^n(x)等价于x³

n=3