已知数列(an)满足a1+2a2+3a3+...+nan=n(n+1)(n+2)求an注:a1,a2 当中a后面的数字是小的因为本人打不来所以看上去很怪
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![已知数列(an)满足a1+2a2+3a3+...+nan=n(n+1)(n+2)求an注:a1,a2 当中a后面的数字是小的因为本人打不来所以看上去很怪](/uploads/image/z/1159257-57-7.jpg?t=%E5%B7%B2%E7%9F%A5%E6%95%B0%E5%88%97%28an%29%E6%BB%A1%E8%B6%B3a1%2B2a2%2B3a3%2B...%2Bnan%3Dn%28n%2B1%29%28n%2B2%29%E6%B1%82an%E6%B3%A8%3Aa1%2Ca2+%E5%BD%93%E4%B8%ADa%E5%90%8E%E9%9D%A2%E7%9A%84%E6%95%B0%E5%AD%97%E6%98%AF%E5%B0%8F%E7%9A%84%E5%9B%A0%E4%B8%BA%E6%9C%AC%E4%BA%BA%E6%89%93%E4%B8%8D%E6%9D%A5%E6%89%80%E4%BB%A5%E7%9C%8B%E4%B8%8A%E5%8E%BB%E5%BE%88%E6%80%AA)
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已知数列(an)满足a1+2a2+3a3+...+nan=n(n+1)(n+2)求an注:a1,a2 当中a后面的数字是小的因为本人打不来所以看上去很怪
已知数列(an)满足a1+2a2+3a3+...+nan=n(n+1)(n+2)求an
注:a1,a2 当中a后面的数字是小的因为本人打不来所以看上去很怪
已知数列(an)满足a1+2a2+3a3+...+nan=n(n+1)(n+2)求an注:a1,a2 当中a后面的数字是小的因为本人打不来所以看上去很怪
a1+2a2+3a3+...+(n-1)a(n-1)=(n-1)n(n+1)
a1+2a2+3a3+...+nan=n(n+1)(n+2)
2试-1式得
nan=3n(n+1)
an=3(n+1)
an=3(n+1)
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