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[√(n+1)-√n]/(n+1)
=[√(n+1)-√n][√(n+1)+√n]/(n+1)[√(n+1)+√n]
=1/(n+1)[√(n+1)+√n]
跟1/n^(3/2)进行比较
lim n→∞ 1/(n+1)[√(n+1)+√n]/1/n^(3/2)
=lim n^(3/2)/(n+1)[√(n+1)+√n]
=lim n^(3/2)/n√n(1+1/n)[√(1+1/n)+1]
=lim 1/(1+1/n)[√(1+1/n)+1]
=1/2>0
因为p级数1/n^(3/2)收敛,所以原级数收敛
=[√(n+1)-√n][√(n+1)+√n]/(n+1)[√(n+1)+√n]
=1/(n+1)[√(n+1)+√n]
跟1/n^(3/2)进行比较
lim n→∞ 1/(n+1)[√(n+1)+√n]/1/n^(3/2)
=lim n^(3/2)/(n+1)[√(n+1)+√n]
=lim n^(3/2)/n√n(1+1/n)[√(1+1/n)+1]
=lim 1/(1+1/n)[√(1+1/n)+1]
=1/2>0
因为p级数1/n^(3/2)收敛,所以原级数收敛
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