lim->0(tanx-x)\(x-sinx)

lim->0(tanx-x)\(x-sinx)
lim->0(tanx-x)\(x-sinx)

lim->0(tanx-x)\(x-sinx)
lim->0(tanx-x)\(x-sinx)
=lim (sec²x-1)/(1-cosx)
=lim(1-cos²x)/(1-cosx) lim1/cos²x
=lim(1-cos²x)/(1-cosx)
=lim(2sinxcosx)/(sinx)
=lim 2cosx
=2

洛必达法则，上下分别求导，直至把x=0可以带进去算