判断正项级数的收敛性ln(1+n)/(n^2)

ln(1+n)/(n^2)和1/n^(3/2)比较[ln(1+n)/(n^2)]/[1/n^(3/2)]=ln(1+n)/(n^(1/2))ln(1+n)/(n^(1/2))求导得2(√n )/(1+n) =0 当 limn->∞所以ln(1+n)/(n^2)