作者ttinff (mmmm)
看板Math
标题Re: [中学代数一题.....
时间Tue May 17 10:51:30 2011
※ 引述《adamchi (adamchi)》之铭言：
: 设n为正整数,且满足 25n^2+24n+34 等於相邻两个正整数的乘积
: 则n=_____
: 麻烦大家~~
(5n+3)^2 = 25n^2 +30n+ 9
(5n+2)^2 = 25n^2 +20n+ 4
=> 25n^2 + 24n +34 = (5n+2)(5n+3)
= 25n^2 +25n +6
=> n= 28
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1F：推 jeff413 :2也可以 05/17 11:39
2F：推 a016258 :(5n+m)(5n+m+1) ， m=0.1.2.3.4 05/17 12:11
3F：推 jeff413 :应该只要看2.3.4就可以了 05/17 12:48
4F：推 tsaifc :17898 05/17 14:53
5F：→ ttinff :拍谢~欠考虑...XD 05/17 17:18