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标题: pppp-1 [打印本页]

作者: pengfei1102 时间: 2006-7-18 13:08
标题: pppp-1
[attachimg]48761[/attachimg]

作者: pengfei1102 时间: 2006-7-19 09:05
另 x=1/2 y=2。则答案为 ; 9/25.. 怎么　怪怪的。是不是题出错了。

作者: lianxyz 时间: 2006-7-19 09:17

Try (x+y

If (x+y)^2 and (x-y)^2 are the powers of 2,then the value of the equation is 2^4xy, thus the result is 16.

作者: pengfei1102 时间: 2006-7-19 09:20

谢谢 i know。 lianxyz 考试成功

作者: anclewu 时间: 2006-7-19 11:25

以下是引用lianxyz在2006-7-19 9:17:00的发言：

Try (x+y

If (x+y)^2 and (x-y)^2 are the powers of 2,then the value of the equation is 2^4xy, thus the result is 16.

能解释清楚些吗? 谢谢

作者: lianxyz 时间: 2006-7-19 13:21

xy=1

2^(x+y)^2/2^(x-y)^2=2^(x+y)^2-(x-y)^2

=2^4xy

= 2^4

=16

Hope it will be helpful.

作者: anclewu 时间: 2006-7-19 13:54

谢谢啦

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