f'(x)=sin(1-cosx)²(1-cosx)'=sin(2sin²x/2)²sinx~sin(2x²/4)²x=sin(x^4/4)x~x^5/4
g'(x)=x^4+x^5
故limf(x)/g(x)=limf'(x)/g'(x)=lim(x^5/4)/(x^4+x^5)=limx/4(1+x)=0
所以f(x)是g(x)的高阶无穷小。
x->0:
t->0
1-cosx=x^2 /2
sin(t^2)=t^2
f(x)=∫_(0 to x^2 /2 ) t^2 dt
=∫_(0 to x^2 /2 ) t^2 dt
=1/3 (x^2 /2)^3
=1/24 x^6
所以,答案是(B)
哦