y=x/(x+1)^1/2换元法令t=(x+1）^1/2t^2=x+1x=t^2-1y=(t^2-1)/t=t-1/tx=t^2-1dx=2tdt原是=（t-1/t)x2tdt=2t^2-2dt=2/3t^3-2t+C把t=(x+1)^1/2带入2/3x(x+1)^(3/2)-2(x+1）^1/2+C
