lim（n趋向于无穷大）(1+√2+√3+…+√n)/n√n
=lim（n趋向于无穷大）1/n*(√1/n+√2/n+√3/n+…+√n/n)=∫（0,1）√xdx=2/3*x^(3/2)|（0,1）=2/3