令√x=t,x=t^2,dx=2tdt∫x/(1+√x)dx=∫t^2/(1+t)*2tdt=2∫(t^3+1-1)/(1+t)dt=2∫[t^2+t+1-1/(1+t)]dt=2/3t^3+t^2+2t-2ln(1+t)+C再反代就可以了
