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1-1/2*nC1+1/3*nC2-…+(-1)^n*(1/(n+1))*nCn=
题目详情
1-1/2*nC1+1/3*nC2-…+(-1)^n*(1/(n+1))*nCn=
▼优质解答
答案和解析
1\(k+1)*nCk=1\(n+1)*(n+1)C(k+1) 所以原式
=-1\(n+1)*[-(n+1)C1++(-1)^(n+1)(n+1)C(n+1)]
=-1\(n+1)*[(1-1)^(n+1)-(n+1)C0]=1\(n+1)
=-1\(n+1)*[-(n+1)C1++(-1)^(n+1)(n+1)C(n+1)]
=-1\(n+1)*[(1-1)^(n+1)-(n+1)C0]=1\(n+1)
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