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In the xy plane, does the line with equation y=3x+2 contain [#permalink]
 26 Apr 2006, 02:23
In the xy 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
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VP
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D...
From the first equation we get
s=3r+2 (this satisfies the GIVEN equation y=3x+r for the values (r,s))
OR
s=4r+9
From seconds equation, we get
s=4r+6
OR
s=3r+2 (this again satisfies)
Combining option 1 AND option 2,
the only soilution that is common is s=3r+2
Hence, it satisfies!
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sm176811 wrote: D...
From the first equation we get
s=3r+2 (this satisfies the GIVEN equation y=3x+r for the values (r,s))
OR
s=4r+9
From seconds equation, we get
s=4r+6
OR
s=3r+2 (this again satisfies)
Combining option 1 AND option 2,
the only soilution that is common is s=3r+2
Hence, it satisfies!
thanks for the explaination.
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Intern
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OA is C... what gives?
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why do you say:
{Combining option 1 AND option 2,
the only soilution that is common is s=3r+2
Hence, it satisfies!
If we need to combine them to eliminate the OR's, then the correct answer should be C.
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[quote="stevenzeng"]OA is C... what gives?[/quote]
see my other post. It's C because you need to combine the information to eliminate the OR. The stmts by themselves do not say definitely that the line contains the points.
There's a key to DS problems: Remember that just because you can't say Yes, doesn't mean you can't say NO. I may not be able to say yes to "does x > 0", for example, but one of the stmts may give me enough information to say it definitely is NOT > 0. That's Sufficient.
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sm176811 wrote: D...
From the first equation we get
s=3r+2 (this satisfies the GIVEN equation y=3x+r for the values (r,s))
OR
s=4r+9
From seconds equation, we get
s=4r+6
OR
s=3r+2 (this again satisfies)
Combining option 1 AND option 2,
the only soilution that is common is s=3r+2
Hence, it satisfies!
If you combine them then automatically the answer choice is C
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Intern
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Would somebody mind explaining how the answer choices fit into what the question is asking? I really don't understand this one...
The way I see it, wouldn't either answer choice be sufficient? Why the need to combine it?
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stevenzeng wrote: Would somebody mind explaining how the answer choices fit into what the question is asking? I really don't understand this one...
The way I see it, wouldn't either answer choice be sufficient? Why the need to combine it?
1) (3r+2-s) (4r+9-s)=0
S can have 2 values -
s = 3r + 2 or s = 4r + 9
If s=3r + 2, it satisfies the eq, but for s = 4r + 9, it does not.
Hence insufficient
2) (4r-6-s) (3r+2-s)=0
Here s can have 2 values.
s=4r-6 or s=3r+2
If s=3r + 2, it satisfies the eq, but if s=4r-6, it does not.
Hence insuff
Taking these two together, the only common value of s = 3r+2. This satisfies the eq. Hence sufficient.
Hence C.
Hope it is clear now.
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However,
Anything multiplied by (3r+2-s) is ZERO, right! Doesn't it mean each of them is sufficient on its own?
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techno123 wrote: However,
Anything multiplied by (3r+2-s) is ZERO, right! Doesn't it mean each of them is sufficient on its own?
Yes, my thoughts exactly too. Is there different way we can look at and understasnd this problem?
Thanks..
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