1/3+2/5+3/7+...+n/(2n+1) 求大神快做急用
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判断下列级数的敛散性n=1到无穷√(2n/(3n-1)),求大神~~~~~~
求极限lim(x→∞)(1/n+2/n+3/n..+n/n)
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一列数:0,-1,-1,-2,-2,-3,-3-,4,-4..第n个数是 (填公式,n是正整数)急用快啊.
1/2^n+1/2n的敛散性,求大神
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求极限lim [ 2^(n+1)+3^(n+1)]/2^n+3^n (n→∞)