设级数∑An收敛,且lim(nAn)=a,证明∑n(An-A(n+1))收敛
设级数∑An收敛,且lim(nAn)=a,证明∑n(An-A(n+1))收敛
设数列{nan}收敛,且级数∑an收敛,证明级数∑n(an-an-1)也收敛
设{nAn}收敛,且级数An收敛,证明:级数n(An-An-1)也收敛
设数列{nan}收敛,级数∑n(an-an-1)也收敛,证明级数∑an收敛
级数∑Bn,∑An-A(n-1)收敛,证明∑An*Bn收敛
证明级数绝对收敛若级数∑an绝对收敛,且an≠-1(n=1,2,…),证明:级数∑an/(1+an)收敛.
有关级数收敛若级数∑an收敛,为什么级数∑an + a(n+1)也收敛?而∑a(2n-1) - a(2n)不一定收敛?
级数收敛性的证明求:设∑an^2收敛,证明:∑an/n绝对收敛?
若级数∑an绝对收敛,且an≠-1(n=1,2,…),证明:级数∑an/(1+an)收敛.
设lim(n→∞)na_n 存在,且级数∑(n=1→∞) n(a_n-a_(n-1))收敛,证明:级数∑(n=1→∞)a
设级数∑(an)^2收敛 则级数∑an/n是收敛还是发散
若正项级数∑(1到n)an收敛,则∑(1到n)根号an/n收敛,求证明.