x+y=10
xy=20
(x^2)(y^2)=?
更新1:
對不起,謝謝你們的回答,但我有些弄錯,我漏了一個加號,應是這樣: (x^2)+(y^2)=?
急~一條數學題
回答 (4)
2010-10-24 7:43 pm
✔ 最佳答案
x+y=10xy=20
(x^2)(y^2)=?
xy = 20
(xy)^2 = 20^2
(x^2)(y^2) = 400
2010-10-25 11:17:12 補充：
2010-10-24 13:25:22 補充
對不起,謝謝你們的回答,但我有些弄錯,我漏了一個加號,應是這樣:
(x^2)+(y^2)=?
(x^2) + (y^2)
= (x+y)^2 - 2xy
= 10^2 - 2(20)
= 100 - 40
= 60
2010-10-24 9:47 pm
x+y=10 ...(1)
xy=20 ...(2)
(x^2)+(y^2)
=(x^2)+(y^2) +2xy-2xy
= (x^2)+2xy +(y^2) -2xy
= (x+y)^2 -2xy ...(3)
Sub (1) and (2) into (3)
(x+y)^2 -2xy
=(10)^2 -2(20)
= 100-40
= 60
2010-10-24 13:49:16 補充：
其實 回答者 001 莊安華
答左d 乜??
點解睇唔明??
xy=20 ...(2)
(x^2)+(y^2)
=(x^2)+(y^2) +2xy-2xy
= (x^2)+2xy +(y^2) -2xy
= (x+y)^2 -2xy ...(3)
Sub (1) and (2) into (3)
(x+y)^2 -2xy
=(10)^2 -2(20)
= 100-40
= 60
2010-10-24 13:49:16 補充：
其實 回答者 001 莊安華
答左d 乜??
點解睇唔明??
2010-10-24 6:40 pm
題目是：
x+y=10
xy=20
(x^2)(y^2)=?Solxy=20x^2y^2=400(x^2)(y^2)=400
x+y=10
xy=20
(x^2)(y^2)=?Solxy=20x^2y^2=400(x^2)(y^2)=400
2010-10-24 6:34 pm
x=4
y=5
(x^2)(y^2)=80
y=5
(x^2)(y^2)=80
收錄日期: 2021-04-23 23:13:46
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20101024000051KK00323