mukgera wrote:In the xy-plane, does the line with equation y = 3x + 2 contains the point (r,s)?
1) (3r+2-s)(4r+9-s) = 0
2) (4r-6-s)(3r+2-s) = 0
OA after some discussion.[/quote-
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r and s should satisfy the eqution of line. so s=3r+2.
Put that value in 1 and it satisfy the condition.
Similary put the same value in 2 and it too satisfy the condition.
So both statements are sufficient to answer the question.
D.
geometry in DS...
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If (r,s) is on the line, then it must be the case that s = 3r+2mukgera wrote:In the xy-plane, does the line with equation y = 3x + 2 contains the point (r,s)?
1) (3r+2-s)(4r+9-s) = 0
2) (4r-6-s)(3r+2-s) = 0
So, the target question can be reworded as "Does s = 3r+2"
(1) If (3r+2-s)(4r+9-s) = 0, then either a) 3r+2-s = 0 or b) 4r+9-s = 0
a) If 3r+2-s = 0 then s = 3r+2 (yes!)
b) If 4r+9-s = 0 then s= 4r+9 (no!)
Insufficient
(2) If (4r-6-s)(3r+2-s) = 0, then either c) 4r-6-s or d) 3r+2-s = 0
c) If 4r-6-s=0 then s = 4r-6 (no!)
d) If 3r+2-s = 0 then s = 3r+2 (yes!)
Insufficient
If statements (1) and (2) are true, then it must be the case that s = 3r+2, in which case (r,s) IS on the line.
Answer is C
Cheers,
Brent
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gmatclubmember
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Brent@GMATPrepNow wrote:If (r,s) is on the line, then it must be the case that s = 3r+2mukgera wrote:In the xy-plane, does the line with equation y = 3x + 2 contains the point (r,s)?
1) (3r+2-s)(4r+9-s) = 0
2) (4r-6-s)(3r+2-s) = 0
So, the target question can be reworded as "Does s = 3r+2"
(1) If (3r+2-s)(4r+9-s) = 0, then either a) 3r+2-s = 0 or b) 4r+9-s = 0
a) If 3r+2-s = 0 then s = 3r+2 (yes!)
b) If 4r+9-s = 0 then s= 4r+9 (no!)
Insufficient
(2) If (4r-6-s)(3r+2-s) = 0, then either c) 4r-6-s or d) 3r+2-s = 0
c) If 4r-6-s=0 then s = 4r-6 (no!)
d) If 3r+2-s = 0 then s = 3r+2 (yes!)
Insufficient
If statements (1) and (2) are true, then it must be the case that s = 3r+2, in which case (r,s) IS on the line.
Answer is C
Cheers,
Brent
Thanks for pointing out my mistake.
In this case we would need both the conditions to arrive at the conclusion that s = 3r+2 and so the answer should be C.
(3r+2-s)(4r+9-s) = (4r-6-s)(3r+2-s) , if 3r+2-s!=0 then 9=-6 which is incorrect so 3r+2-s has to be 0 and then it would satisfy the equation.
Is that correct.
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You're absolutely correct, gmatclubmember.(3r+2-s)(4r+9-s) = (4r-6-s)(3r+2-s) , if 3r+2-s!=0 then 9=-6 which is incorrect so 3r+2-s has to be 0 and then it would satisfy the equation.
Although, for the benefit of others, I should point out that by "!=0" you mean "not equal to zero".
Cheers,
Brent
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