2. If x+y+z+t=a, x^2+y^2+z^2+t^2=b, x^3+y^3+z^3+t^3=c, x^4+y^4+z^4+t^4=d,
then xyz+xyt+xzt+yzt=? xyzt=?
(in terms of a,b,c,d)
更新1:
2. xyz+...+yzt=(a^3-3ab+2c)/3!, xyzt=(a^4-6a^2 b+8ac+3b^2 -6d)/4!
2. xyz+...+yzt=(a^3-3ab+2c)/3!, xyzt=(a^4-6a^2 b+8ac+3b^2 -6d)/4!
收錄日期: 2021-04-21 22:30:50
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20131023000051KK00033