LIM(X趋向0)(tanx-x)/(x-sinx)

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LIM(X趋向0)(tanx-x)/(x-sinx)
LIM(X趋向0)(tanx-x)/(x-sinx)

LIM(X趋向0)(tanx-x)/(x-sinx)
LIM(X趋向0)(tanx-x)/x³=LIM(X趋向0)(sec²x-1)/(3x²)=LIM(X趋向0)(1-cos²x)/(3x²cos²x)
=LIM(X趋向0)(sinx/x)²/(3cos²x)=1/3
LIM(X趋向0)x³/(x-sinx)=LIM(X趋向0)3x²/(1-cosx)=LIM(X趋向0)3x²/2 sin²(x/2)
=LIM(X趋向0) 6 [(x/2)/sin(x/2)]²=6
原极限=(1/3)6=2

运用罗比达法则
原式=lim(x->0) (sec^2x-1)/(1-cosx)
=lim(x->0) (2sec^2xtanx)/(sinx)
=2*lim(x->0) 1/cos^3x
=2