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sykedaddy
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 Posted: Fri Jul 06, 2007 5:01 pm Post subject: GMAT PREP DS |
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In the xy- plane, does the line with equation y=3x + 2 contain point (r,s)?
(1) (3r+2-s)(4r+9-s)=0
(2) (4r-6-s) (3r+2-s)=0
I say that they equal each other....but get stuck going down that road...no variables...
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givemeanid
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| Posted: Fri Jul 06, 2007 5:16 pm Post subject: |
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Does y=3x + 2 contain point (r,s)?
In other words, is s = 3r + 2.
Rearranging the equations, the question is whether 3r + 2 - s = 0?
(1) (3r+2-s)(4r+9-s) = 0
So, either 3r+2-s = 0 or 4r+9-s = 0
NOT SUFFICIENT.
(2) (4r-6-s) (3r+2-s) = 0
So, either 4r-6-s = 0 or 3r+2-s = 0
NOT SUFFICIENT.
Combining both, 3r+2-s = 0.
SUFFICIENT.
Answer is (C).
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eby_98
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| Posted: Thu Jul 12, 2007 7:46 pm Post subject: |
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| Is (c) the correct answer? |
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gabriel
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| Posted: Fri Jul 13, 2007 5:25 am Post subject: Re: GMAT PREP DS |
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| sykedaddy wrote: | In the xy- plane, does the line with equation y=3x + 2 contain point (r,s)?
(1) (3r+2-s)(4r+9-s)=0
(2) (4r-6-s) (3r+2-s)=0
I say that they equal each other....but get stuck going down that road...no variables... |
DS questions go in the DS section  ... |
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sykedaddy
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| Posted: Mon Jul 16, 2007 7:18 am Post subject: |
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Sorry...yes ans. is C
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bingojohn
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| Posted: Wed Aug 08, 2007 6:06 am Post subject: |
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| givemeanid wrote: | Does y=3x + 2 contain point (r,s)?
In other words, is s = 3r + 2.
Rearranging the equations, the question is whether 3r + 2 - s = 0?
(1) (3r+2-s)(4r+9-s) = 0
So, either 3r+2-s = 0 or 4r+9-s = 0
NOT SUFFICIENT.
(2) (4r-6-s) (3r+2-s) = 0
So, either 4r-6-s = 0 or 3r+2-s = 0
NOT SUFFICIENT.
Combining both, 3r+2-s = 0.
SUFFICIENT.
Answer is (C). |
What does the emphasized text above mean. In other words how do you combine the two equations to arrive at 3r + 2 - s = 0, definitively? Please explain. |
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givemeanid
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| Posted: Wed Aug 08, 2007 8:18 am Post subject: |
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3r+2-s = 0 is the only condition that is satisfied by BOTH 1 and 2.
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