y=1/3x求导则么求？y=3*√(1-x^2/4) ？

y=3*√(1-x^2/4)=3*(1-x^2/4)^(1/2)
所以y=3*(1/2)(1-x^2/4)^(-1/2)*(1-x^2/4)'
=(3/2)*1/√(1-x^2/4)*(-x/2)
=-(3/4)x/√(1-x^2/4)
对不起刚才做错了

y=1/3x
如果是y=(1/3)x,y'=1/3
如果是y=1/(3x),y'=-1/(3x^2)

y'=1/3

y'=3*[1/2*(1-x^2/4)^2]*(1-x^2/4)'=-3x/(4+x^4/4-2x^2)