limx趋向于+无穷 √[x(x+1)]-1=+∞打错了~~是-x不是-1呢limx趋向于+无穷 √[x(x+1)]-x=lim [x(x+1)- x²]/{√[x(x+1)]+x}=lim x/{√[x(x+1)]+x}=lim 1/{√[1+1/x]+1}=1/2