答：y=[1-√x-(1+√x)]÷[(1+√x)(1-√x)]=(1-√x-1-√x) ÷ (1-x) 分母中有平方差公式的应用=-2√x /(1-x)求导：y'(x)=-2*(1/2)*(1/√x) /(1-x)+2√x*(-1)/(1-x)^2=-1/[(1-x)√x)]-2√x /(1-x)^2=-(1-x)/[√x(1-x)^...