高数!当x趋于0时,f(x)=x-sinax与g(x)=(x^2)ln(1-bx)为等价
当x趋于0时,f(x)=x-sinax与g(x)=(x^2)ln(1-bx)为等价无穷小,则a=?,b=?
李莉蓉回答:
g(x)~-bx^3
limf(x)/g(x)=-lim(x-sinax)/bx^3=-lim(1-acosax)/3bx^2=-lim(1-cosx)/3bx^2=-lim(x^2/2)/3bx^2=-1/6b=1
b=-6
lim(1-acosax)=0,a=1
荆海英回答:
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