Question

f(x)= x-sinx/x+sinx 的倒数

Answer 1

是求 f(x)=(x-sinx)/(x+sinx) 的导数吧,

f'(x)=[(x-sinx)'*(x+sinx)-(x-sinx)*(x+sinx)']/(x+sinx)^2

=[(1-cosx)*(x+sinx)-(x-sinx)*(1+cosx)]/(x+sinx)^2

=2(sinx-xcosx)/(x+sinx)^2.