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lim(x→0)(x^2+cosx-2)/(x^3)*ln(1+x)怎么算
写错了,lim(x→0)(x^2+2cosx-2)/(x^3)*ln(1+x).
人气:130 ℃ 时间:2020-01-29 11:44:18
解答
lim(x→0)(x^2+cosx-2)/(x^3)*ln(1+x)
=lim(x→0)(0+1-2)*(ln(1+x)/(x^3))
=lim(x→0) -(ln(1+x)/(x^3))
=im(x→0) -1/[(1+x)*(3x^2)]
=im(x→0) -1/(3x^2)
负无穷im(x→0)(x^2+2cosx-2)/(x^3)*ln(1+x)=lim(x→0)(x^2+2cosx-2)*(ln(1+x)/(x^3))把cosx,ln(1+x)展开cosx=1-x^2/2+x^4/24……ln(1+x)=x-x^2/2+x^3/2+……lim(x→0)(x^2+2cosx-2)/[(x^3)*(ln(1+x)]=lim(x→0)(x^2+2-x^2+x^4/12-2)/(x^3)[(x-x^2/2+x^3/2)]=lim(x→0)(x^4/12)/(x^3)[(x-x^2/2+x^3/2)]=lim(x→0)(x^4/12)/(x^3)x=1/12那一步写错了,后面是对的im(x→0)(x^2+2cosx-2)/(x^3)*ln(1+x)=lim(x→0)(x^2+2cosx-2/[(x^3))(ln(1+x)]把cosx,ln(1+x)展开cosx=1-x^2/2+x^4/24……ln(1+x)=x-x^2/2+x^3/2+……lim(x→0)(x^2+2cosx-2)/[(x^3)*(ln(1+x)]=lim(x→0)(x^2+2-x^2+x^4/12-2)/(x^3)[(x-x^2/2+x^3/2)]=lim(x→0)(x^4/12)/(x^3)[(x-x^2/2+x^3/2)]=lim(x→0)(x^4/12)/(x^3)x=1/12
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