急求【初一奥数题】戳进来题目有图.

\u6025\u6c42\u3010\u521d\u4e00\u5965\u6570\u9898\u3011\u6233\u8fdb\u6765\u9898\u76ee\u6709\u56fe

n^2+[n(n+1)]^2+(n+1)^2=[n*(n+1)+1]^2
\u7b49\u5f0f\u53f3\u4fa7\u5c55\u5f00:[n(n+1)]^2+2n(n+1)+1
\u540e\u9762\u90a3\u4e2a2n(n+1)+1=2n^2+2n+1=(n^2)+(n^2+2n+1)=n^2+(n+1)^2

1\u3001\u80fd\u770b\u52306\u4e2a\uff0c\u5b9e\u9645\u5171\u670910\u4e2a\u3002
2\u3001\u89c4\u5f8b\u662f\uff1a\u6bcf\u5c42\u6309\u589e\u52a01\u30012\u30013\u30014\u30015\u30016\u30017.....\u589e\u52a0\u3002\u7b2c\u516d\u5c42\u662f\uff1a1+2+3+4+5+6=21\u4e2a\uff0c
\u7b2c\u4e00\u5c42\uff1a1\u4e2a\uff0c\u7b2c\u4e8c\u5c42\uff1a1+2=3\u4e2a\uff0c\u7b2c\u4e09\u5c42\uff1a1+2+3=6\u4e2a\uff0c\u7b2c\u56db\u5c42\uff1a1+2+3+4=10\u4e2a\uff0c\u7b2c\u4e94\u5c42\uff1a1+2+3+4+5=15\u4e2a
\u603b\u6570\uff1a1+3+6+10+15+21=56\uff08\u4e2a\uff09

答案是2015/4028(应该是对的)
话说题目上第一个括号里是(1-1/ 2的二次)吗?
过程:原式=(1+1/2)(1-1/2)(1+1/3)(1-1/3)(1+1/4)(1-1/4)....(1+1/2013)
(1-1/2013)(1+1/2014)(1-1/2014)【平方差公式】
=3/2*1/2*4/3*2/3*5/4*3/4*.....*2014/2013*2012/2013*2015/2014*2013/2014
【约分后】=1/2*2015/2014
=2015/4028

  • 鎬ユ眰銆愬垵涓濂ユ暟棰樸戞埑杩涙潵棰樼洰鏈鍥
    绛旓細鍚庨潰閭d釜2n(n+1)+1=2n^2+2n+1=(n^2)+(n^2+2n+1)=n^2+(n+1)^2
  • 鎬ユ眰銆愬垵涓濂ユ暟棰樸戞埑杩涙潵棰樼洰鏈鍥.
    绛旓細绛旀鏄2015/4028锛堝簲璇ユ槸瀵圭殑锛夎瘽璇棰樼洰涓婄涓涓嫭鍙烽噷鏄(1-1/ 2鐨勪簩娆)鍚楋紵杩囩▼锛氬師寮=锛1+1/2锛夛紙1-1/2锛夛紙1+1/3锛夛紙1-1/3锛夛紙1+1/4锛夛紙1-1/4锛...锛1+1/2013锛夛紙1-1/2013锛夛紙1+1/2014锛夛紙1-1/2014锛夈愬钩鏂瑰樊鍏紡銆=3/2*1/2*4/3*2/3*5/4*3/4*...*2014...
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