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Weird Data Sufficiency

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by MonicaKhan » Sun Apr 22, 2007 7:16 am
Here's a Data Sufficiency question from the GMATPrep software that I can't figure out the answer to:

In the x-y plane, does the line with equation y = 3x + 2 contain the point (r,s)?

(1) (3r + 2 - s)(4r +9 - s) = 0
(2) (4r - 6 - s)(3r + 2 - s) = 0

I think each of these statements are sufficient to answer the question, but the answer is supposedly C. Not sure why, so any insights would be greatly appreciated. Thanks!
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Source: — Data Sufficiency |

Re: Weird Data Sufficiency

by jayhawk2001 » Sun Apr 22, 2007 8:36 am
MonicaKhan wrote:Here's a Data Sufficiency question from the GMATPrep software that I can't figure out the answer to:

In the x-y plane, does the line with equation y = 3x + 2 contain the point (r,s)?

(1) (3r + 2 - s)(4r +9 - s) = 0
(2) (4r - 6 - s)(3r + 2 - s) = 0

I think each of these statements are sufficient to answer the question, but the answer is supposedly C. Not sure why, so any insights would be greatly appreciated. Thanks!
1 - insufficient. We know (3r + 2 -s = 0) OR (4r + 9 - s = 0).

2 - insufficient. We know (4r - 6 - s = 0) OR (3r + 2 - s = 0)

1 and 2 together are sufficient.
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by MonicaKhan » Sun Apr 22, 2007 12:59 pm
Duh, I don't know how I missed that. Thanks for the clarification!
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by Prasanna » Mon Apr 23, 2007 5:23 am
Sorry, I am not able to understand why it would be C. From (1) and (2) we have two equations in each, which can be solved to answer the question.

What is that I am missing here? Would be grateful if you could explain.
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by ronniecoleman » Thu Dec 18, 2008 1:34 am
IMO C
1 let (3r + 2 - s) = K
(4r +9 - s) = L
(4r - 6 - s) = P

K*L = 0
K*P = 0

Now if K ! =0 Then L = P =0
but they (4r - 6 - s) != )(4r +9 - s) ( on any day they are not equal )

hence K =0
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