=lim(tanx-sinx)/x³(x-cosx)*lim1/(√(1+tanx)+√(1+sinx))
=1/2lim(sec²x-cosx)/(4x³-3x²cosx+x³sinx)
=1/2lim(1-cosx)/(4x³-3x²cosx+x³sinx)*lim(1+cosx+cos²x)/cos²x
=3/2limsinx/(12x²-6xcosx+3x²sinx+3x²sinx+x³cosx)
=3/2limsinx/x*lim1/(12x-6cosx+6xsinx+x²cosx)
=3/2*(-1/6)
=-1/4