請問這條數怎樣做???
回答 (2)
2007-07-05 8:56 pm
✔ 最佳答案
(a+b)(b+c)(c+a)=acc+abb+baa+bcc+cbb+caa+2abc
=a(cc+bb)+b(aa+cc)+c(aa+cc)+2abc
>=a(2bc)+b(2ac)+c(2ab)+2abc
=8abc
2007-07-05 12:59:58 補充：
(x-y)^2 =0xx-2xy yy =0xx yy =2xyput x=a,y=baa bb =2absimularly,bb cc =2bc aa cc =2ac
2007-07-05 13:02:59 補充：
佢只係話正數,所以可以係0.3, 0.幾咁,最細唔係1
參考: me
2007-07-05 8:28 pm
設a,b,c最細都係1~
left hand side:(1+1)(1+1)(1+1)
=2*2*2
=8
right hand side:8(1)(1)(1)
=8
最細都等於8~所以(a+b)(b+c)(c+a)>=8abc
left hand side:(1+1)(1+1)(1+1)
=2*2*2
=8
right hand side:8(1)(1)(1)
=8
最細都等於8~所以(a+b)(b+c)(c+a)>=8abc
收錄日期: 2021-04-13 14:47:49
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070705000051KK01259