coordinate point
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Source: Beat The GMAT — Data Sufficiency |
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hk
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Can anybody please explain this???
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x2suresh
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Given ab<>0
(-a,b),(-b,a) are on the same quadrant.
clearly from the above. -a and -b have same sign also a and b have same sign.
ab>0 ( both are -ve or +ve)
these points exists in either I quadrant or III quadrant.
(1) xy>0
clearly not sufficient. We don't how they are related to either x or y
(2) ax>0
ax>0 clearly tells the a and x HAVE same sign.
but we don't know the sign of y.
not sufficient
combined
a,b,y,z have same sign.
(-a,b),(-b,a) (-x,y) exists in same quadrant ( It can be either I or III)
Question: is (-X,Y) same quadrant? "Ans" : Yes.
Sufficient.
C
(-a,b),(-b,a) are on the same quadrant.
clearly from the above. -a and -b have same sign also a and b have same sign.
ab>0 ( both are -ve or +ve)
these points exists in either I quadrant or III quadrant.
(1) xy>0
clearly not sufficient. We don't how they are related to either x or y
(2) ax>0
ax>0 clearly tells the a and x HAVE same sign.
but we don't know the sign of y.
not sufficient
combined
a,b,y,z have same sign.
(-a,b),(-b,a) (-x,y) exists in same quadrant ( It can be either I or III)
Question: is (-X,Y) same quadrant? "Ans" : Yes.
Sufficient.
C
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Uri
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Testing with different numbers [eg. (2,3), (-2,3), (-2,-3) and (2,3)], we find that he points are in the 2nd quadrant.
(1) implies that x and y are either in the 1st quadrant or in the 3rd quadrant. So, it is not sufficient.
(2) implies that x> 0, since a>0 in order to satisfy the criteria. Since we don’t know about y, we can not say whether (x,y) lies in the same quadrant as (-a,b) and (-b,a).
Combining these two, (x,y) is in the 1st quadrant. So, it is not in the same quadrant as (-a,b) and (-b,a). So, answer is (C)
I have attached the solution for better clarification. Hope this helps.
(1) implies that x and y are either in the 1st quadrant or in the 3rd quadrant. So, it is not sufficient.
(2) implies that x> 0, since a>0 in order to satisfy the criteria. Since we don’t know about y, we can not say whether (x,y) lies in the same quadrant as (-a,b) and (-b,a).
Combining these two, (x,y) is in the 1st quadrant. So, it is not in the same quadrant as (-a,b) and (-b,a). So, answer is (C)
I have attached the solution for better clarification. Hope this helps.
- Attachments
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- Answer.doc
- This file shows the test performed with different numbers and how we can find the solution from them.
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