Correct the following caculations.
1. (x+y)^2=x^2+y^2
S1 to S2 ~ Mathematics ~ Learning from the Mistakes ~
2007-07-19 4:33 am
回答 (3)
2007-07-19 5:11 am
(x+y)^2=
當成直式
當成__ 十位 個位
________|__/
________v v
________x+y
X_______x+y
-------------------
___x^2+xy+0
_____xy+y^2
-------------------
x^2+2xy+y^2
（不用理會＿＿＿＿＿）
so,(x+y)^2=x^2+2xy+y^2
當成直式
當成__ 十位 個位
________|__/
________v v
________x+y
X_______x+y
-------------------
___x^2+xy+0
_____xy+y^2
-------------------
x^2+2xy+y^2
（不用理會＿＿＿＿＿）
so,(x+y)^2=x^2+2xy+y^2
2007-07-19 4:37 am
(x+y)^2
=x^2 + 2xy + y^2
=/= x^2+y^2
2007-07-18 20:37:59 補充：
(x y)^2 = x^2 y^2 only when x=0 or y=0
=x^2 + 2xy + y^2
=/= x^2+y^2
2007-07-18 20:37:59 補充：
(x y)^2 = x^2 y^2 only when x=0 or y=0
收錄日期: 2021-04-13 00:48:42
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070718000051KK04471