limx->0 (sinx-xcosx)/x^3 极限 0.

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limx->0 (sinx-xcosx)/x^3 极限 0.

limx->0 (sinx-xcosx)/x^3 极限 0.
limx->0 (sinx-xcosx)/x^3 极限 0.

limx->0 (sinx-xcosx)/x^3 极限 0.
罗比达法则解法.
原式=lim(x->0)[(sinx-xcosx)/(sinx)^3]
=lim(x->0)[(cosx-cosx+xsinx)/(3sin²x)] (0/0型极限,应用罗比达法则)
=lim(x->0)[x/(3sinx)] (化简)
=(1/3)lim(x->0)(x/sinx)
=(1/3)*1 (应用重要极限lim(x->0)(sinx/x)=1)
=1/3.

如图limx→0 (sinx-xcosx)/sin^3x =(1-xcotx)/sin 2;x =(tanx-x)/x 3; 利用等价无穷小:sinx∽x∽tanx =(sec 2;x-1)/3x 2;