求教：涛涛GWD31－5－4

ddcat910 · 发表于 2006-6-21 11:49:00

这是我在涛涛的GWD上见到的，没有思路，请教各位NN。

√[2√63 + 2/(8+3√7)] =

A. 8 + 3√7

B. 4 + 3√7

C. 8

D. 4

E. √7

答案：D

kallyli · 发表于 2006-6-21 13:32:00

1/(8+3√7)*1/(8-3√7)*(8-3√7)=2(8-3√7)=16-6√7

2√63=6√7

add them up

ddcat910 · 发表于 2006-6-21 13:56:00

Thanks

captain_ma · 发表于 2006-9-20 22:05:00

very strange!i can't slove the problem too at first glance!

jingle0915 · 发表于 2010-7-30 15:28:36

very strange!i can't slove the problem too at first glance!

LUXIN19950206 · 发表于 2018-5-17 17:55:38

kallyli 发表于 2006-6-21 13:32
1/(8+3√7)*1/(8-3√7)*(8-3√7)=2(8-3√7)=16-6√72√63=6√7add them up

第一排没看懂

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