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Letx .  If , then

Let [x] = x2 – 2.  If [2] - [x] = x2, then x =


(A)

√2


(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Nova Press: Set D - Defined functions

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Posted: 01/25/2013 10:34
Wht only substitute in the left side id The equation?
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Posted: 01/26/2013 00:02
Not sure what your question was Andres.
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Posted: 01/26/2013 10:48
In the explanation they only substitute the value of x in the left side:

2-x = x^2
The left side is 2-x
The rigth side is x^2

You need to substitute x = x^2 - 2 for all valúes of x in both sides of The equation?

The explanation goes:
2- (x^2-2) = x^2

If You substitute x in The right You should get : (x^2-2)^2?

Hope that I explaned better!
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Posted: 08/01/2013 06:21
I agree with Andres. I don't know if I did the question wrong, but get 2 as the answer. I went about the problem in 2 ways, here is what I did:
1) I saw that both equations were equal so I discarded the first one solving for x and just solved for the roots of
x^2-x-2=0 which are 2, -1
So I chose 2 as the answer.
2) the second way was when I realized that maybe I might have to substitute for x and I followed what Andres did:
x^2-4 x+4 = x^2-4 which still gives back the answer as 2.

Maybe it's the way I'm reading it but I think my work is right?
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Posted: 08/02/2013 07:31
Mike, Andres, sorry for the trouble. There was an error in this question stem. We fixed it in the database and an update will fix the app soon. In the mean time, please see the corrected question and solution on the website http://www.arcadiaprep.com/discussion/messages/738

You can log in using the same id and pw you created in the app. Thanks.
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Posted: 08/01/2013 08:58
This question does not look right. Andres and Mike, let us check and get back.
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Posted: 08/12/2013 16:22
Joel, thanks for notifying us. We fixed it, it will be in the next update. Thanks.
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Letx .  If , then 
Posted: 08/27/2013 20:47
Next update not out yet
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