2 replies to this topic

[vietnamesegauss89]

Cho n N*,n 3,k R.Xét n số thực ,,..., thỏa mãn =1 .Tìm giá trị lớn nhất của biểu thức:

S= (.......)-k...

Edited by vietnamesegauss89, 03-12-2005 - 15:58.

[shinichikudo]

Bài này có lẽ là 1 tổng quát khá mạnh của bài dự tuyển 1996 có nội dung:
cho a,b,c,d>0 thỏa mãn a+b+c+d=1.CMR:abc+abd+acd+bcd

[Merlyn]

Nếu k http://dientuvietnam...metex.cgi?n^{2} thì Smin=0.Nếu k>http://dientuvietnam...mimetex.cgi?n^2 thì Smin= http://dientuvietnam...metex.cgi?k_{0} http://dientuvietnam...metex.cgi?x_{1} http://dientuvietnam...metex.cgi?x_{2} ...http://dientuvietnam.net/cgi-bin/mimetex.cgi?k_{0} =http://dientuvietnam.net/cgi-bin/mimetex.cgi?n^{2}- http://dientuvietnam...metex.cgi?x_{i} }. http://dientuvietnam...metex.cgi?x_{n} =min{ http://dientuvietnam...metex.cgi?x_{i} } .Đặt Q= ( http://dientuvietnam.net/cgi-bin/mimetex.cgi?x_{3} ... http://dientuvietnam.net/cgi-bin/mimetex.cgi?x_{1} P- http://dientuvietnam.net/cgi-bin/mimetex.cgi?x_{1} http://dientuvietnam.net/cgi-bin/mimetex.cgi?x_{2} ... http://dientuvietnam.net/cgi-bin/mimetex.cgi?x_{n} 0 thì S ( http://dientuvietnam.net/cgi-bin/mimetex.cgi?x_{1} + http://dientuvietnam.net/cgi-bin/mimetex.cgi?x_{1} , http://dientuvietnam.net/cgi-bin/mimetex.cgi?x_{n} ) S((http://dientuvietnam.net/cgi-bin/mimetex.cgi?x_{2} ,..., http://dientuvietnam.net/cgi-bin/mimetex.cgi?x_{n-1} ,( )/2.Làm tiếp như bài dự tuyển 96.
KL:
nếu k thì Smax=
nếu k< thì Smax=+ (-k).

Edited by HFZMATHS, 08-12-2005 - 17:04.