1.当x4时,
y=x²-3x-4
y'=2x-3
2.y=ln(1-x/1+x)
=ln[1/(1+x)]
=-ln(1+x)
y'=-1/(1+x)
3.y=(ax²+bx+c)^(1/3)
y'=(1/3)*(ax²+bx+c)^(-2/3)*(2ax+b)
4.y=cosx*cos2x*cos4*cos8x
=16sinx*cosx*cos2x*cos4x*cos8x/(16sinx)
=sin16x/(16sinx)
y'=1/16*(16cos16x*sinx-cosx*sin16x)/(sinx)^2