见到根号下是一次函数肯定换元,t=genhao(ax+b),ax+b=t^2,adx=2tdt,
jifen[2tdt/(t+m)]=2*jifen[1-m/(t+m)]dt=t-mln(t+m)+c
=gen(ax+b)-mln(gen(ax+b)+m)+c