您想问的是:已知数列的前n项和Sn与数列通项an的关系式，求数列通项公式?一般规律如下:供参考，请笑纳。如果有实例，可能更容易讲解。
又因为 Sn+m−1=a1+an+m−12(n+m−1) ,所以由 an+am>0 能得到 Sn+m−1>0 题1: {an} 为等差数列, a2003>0,a2004<0,a2003+a2004>0 ,求使得 Sn>0 成立的最大 n 值为( ) A.4005 B.4006 C.4007 D.4008 极简分析:利用结论: ...
将an=Sn-Sn-1带入an+1和sn的关系，就可以得到一个有关an+1和an的关系式，再用构造发求通项公式。要注意构造发用的时候n的取值可能会变化！
an+sn=1 sn=-an+1 s(n-1)=-a(n-1)+1 两式相减，得 sn-s(n-1)=-an+a(n-1)=an 即2an=a(n-1) an/a(n-1)=1/2 可见，这是个等比数列 an=1/2*(1/2)^(n-1) =(1/2)^n 你好，这是这一题的答案 当 $n=1$ 时，a_1 + S_1 = 2a_1 = 1 a_1 = \frac{...
（2）Sn=f(an)型即Sn是关于an的函数：这种类型的通项公式，主要有2个思路：保留Sn或者保留an，即Sn与an两个只能留一个。基本方法：当n=1时，S1=f(a1)，可求出a1；思路1-保留Sn：当n≥2时，Sn=f(Sn-S(n-1))；此时可求出Sn=f(n)，再按照上面的方法求解即可。思路2-保留an：当n≥2时，an=Sn...
回答：sn=a1+a2+...+an sn+1=a1+a2+...+an+1
答案解析 查看更多优质解析 解答一 举报 Sn - Sn-1 = An 解析看不懂?免费查看同类题视频解析查看解答 更多答案(1) 相似问题 Sn与an的相互转化 Sn=1/2(an+1/an),求an,用数学归纳法证明 要特别详细过程 Sn2=an(Sn-1/2),求an 特别推荐 热点考点 2022年高考真题试卷汇总 2022年高中期中试卷汇总 202...
Method 1: Enter *#06# on the dialer and the SN will appear on your screen (applicable to the phones and tablets that support SIM cards). Method 2: Check it in Settings. An example is given below based on EMUI 10: Open Settings. Scroll down to the bottom and touch About phone. Loca...
-D assembly1 assembly2Verifies that two assemblies differ only by signature. This is often used as a check after an assembly has been re-signed with a different key pair. -e assembly outfileExtracts the public key fromassemblyand stores it inoutfile. ...
Sn9 B a is an exception where the Si-OB2 bond is ruptured and the Sn-OB distances reduce considerably. The M-OW distances in M9 B b are shorter than in perfectly tetrahedral M(IV) sites and hence interactions with water are enhanced as verified by adsorption energies (e.g., E ad1...