(tanx-sinx)/[(sinx)^3]的极限是?x趋于0

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(tanx-sinx)/[(sinx)^3]的极限是?x趋于0

(tanx-sinx)/[(sinx)^3]的极限是?x趋于0
(tanx-sinx)/[(sinx)^3]的极限是?x趋于0

(tanx-sinx)/[(sinx)^3]的极限是?x趋于0
lim[x→0](tanx-sinx)/sin³x
=lim[x→0](1/cosx-1)/sin²x
=lim[x→0](-sinx/cos²x)/(2sinxcosx) [罗比塔法则]
=lim[x→0](-1/2cos³x)
=-1/2

原极限=
lim (tanx-sinx)/(sinx)^3
=lim (tanx-sinx)x^3
=lim [1/(cosx)^2-cosx]/3x^2
=lim (sinx)^2/3(cosx)^2 x^2
=(1/3)lim x^2/x^2
=1/3