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标题: GWD15-23 [打印本页]

作者: adamkchim 时间: 2008-2-22 08:07
标题: GWD15-23

Q23:

If x ≥ 0 and x = , then, in terms of y, x =

A. – 4y

C. y

D. 4y

E. 4y²

Answer:

作者: adamkchim 时间: 2008-2-22 08:29

If x>or = 0 and x=(8xy-16y^2)^ (1/2)

Ans: 4y

Please explan it.

Thanks!

作者: howren 时间: 2008-2-22 09:03

这题太简单，等式两边同时平方，得出：

x^2=8xy-16y^2

x^-8xy-16y^2=0

(x-4y)^2=0

x=4y

作者: adamkchim 时间: 2008-2-22 09:08

Thanks!

I got it now

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