1.数列{an}的通项公式是an=1/√n+√n+1,若前n项和为10.则项数n为?ps:√是根号哦.2.an=n*3^n,求Sn.3.an=(n+3)*2^n-2,求Sn.因为我是初三自学的,能让我看懂就好了,过程思路好就行,尤其是后面那两题,.
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![1.数列{an}的通项公式是an=1/√n+√n+1,若前n项和为10.则项数n为?ps:√是根号哦.2.an=n*3^n,求Sn.3.an=(n+3)*2^n-2,求Sn.因为我是初三自学的,能让我看懂就好了,过程思路好就行,尤其是后面那两题,.](/uploads/image/z/650510-62-0.jpg?t=1.%E6%95%B0%E5%88%97%7Ban%7D%E7%9A%84%E9%80%9A%E9%A1%B9%E5%85%AC%E5%BC%8F%E6%98%AFan%3D1%2F%E2%88%9An%2B%E2%88%9An%2B1%2C%E8%8B%A5%E5%89%8Dn%E9%A1%B9%E5%92%8C%E4%B8%BA10.%E5%88%99%E9%A1%B9%E6%95%B0n%E4%B8%BA%3Fps%3A%E2%88%9A%E6%98%AF%E6%A0%B9%E5%8F%B7%E5%93%A6.2.an%3Dn%2A3%5En%2C%E6%B1%82Sn.3.an%3D%28n%2B3%29%2A2%5En-2%2C%E6%B1%82Sn.%E5%9B%A0%E4%B8%BA%E6%88%91%E6%98%AF%E5%88%9D%E4%B8%89%E8%87%AA%E5%AD%A6%E7%9A%84%2C%E8%83%BD%E8%AE%A9%E6%88%91%E7%9C%8B%E6%87%82%E5%B0%B1%E5%A5%BD%E4%BA%86%2C%E8%BF%87%E7%A8%8B%E6%80%9D%E8%B7%AF%E5%A5%BD%E5%B0%B1%E8%A1%8C%2C%E5%B0%A4%E5%85%B6%E6%98%AF%E5%90%8E%E9%9D%A2%E9%82%A3%E4%B8%A4%E9%A2%98%2C.)
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