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# M31-35

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Math Expert
Joined: 02 Sep 2009
Posts: 51035

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14 Jun 2015, 13:54
00:00

Difficulty:

35% (medium)

Question Stats:

69% (01:15) correct 31% (01:16) wrong based on 48 sessions

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In which quadrant of the coordinate plane does the point $$(x,y)$$ lie?

(1) $$xy = 7$$

(2) $$5x + 7y < -\frac{1}{2}$$

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Joined: 02 Sep 2009
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14 Jun 2015, 13:54
1
Official Solution:

In which quadrant of the coordinate plane does the point $$(x,y)$$ lie?

(1) $$xy = 7$$. This implies that $$x$$ and $$y$$ are either both negative or both positive, thus $$(x,y)$$ lies either in III quadrant or in I quadrant. Not sufficient.

(2) $$5x + 7y < -\frac{1}{2}$$. Both $$x$$ and $$y$$ can be negative or one of them can be negative and another positive. Not sufficient.

Notice that from this statement it's NOT possible both $$x$$ and $$y$$ to be positive: $$5x + 7y = positive + positive = positive$$, not negative number $$-\frac{1}{2}$$.

(1)+(2) Since (2) rules out possibility of both $$x$$ and $$y$$ being positive, then from (1) we are left with negative $$x$$ and $$y$$: $$(x,y)$$ lies either in III quadrant. Sufficient.

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24 Jul 2015, 22:19
1
I think this is a high-quality question and I agree with explanation. The link to the discussion in the website is broken.

Thanks
Aurion
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25 Jul 2015, 01:11
Aurion wrote:
I think this is a high-quality question and I agree with explanation. The link to the discussion in the website is broken.

Thanks
Aurion

Thank you for reporting. We are looking into it.
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30 Mar 2018, 19:53
Bunuel I'm not sure that how "x and y are either both negative or both positive, lies either in III quadrant or in I quadrant., " and Both xx and yy can be negative or one of them can be negative and another positive." Please provide detailed solution.
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31 Mar 2018, 00:19
1
Bunuel I'm not sure that how "x and y are either both negative or both positive, lies either in III quadrant or in I quadrant., " and Both xx and yy can be negative or one of them can be negative and another positive." Please provide detailed solution.

1. Check this: https://gmatclub.com/forum/math-coordin ... 87652.html

The first quadrant consists of all points with positive x and y coordinates. The product of x and y coordinates = positive.
The third quadrant consists of all points with negative x and y coordinates. The product of x and y coordinates = positive.

2. $$5x + 7y < -\frac{1}{2}$$.

Here if both x and y are positive, 5x + 7y, would have been positive, NOT negative, so both x and y cannot be negative. Which means that either both of them are negative or one of them is negative and another positive.
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24 Aug 2018, 06:05
02 min 11 sec
than the general system result
of 11 min 14 sec

Could you please explain the later statement. " You time result is better
than the general system result
of 11 min 14 sec" what does it mean? general systemresult? chetan2u @sayantc2k Bunuel
Math Expert
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Posts: 51035

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24 Aug 2018, 06:09
02 min 11 sec
than the general system result
of 11 min 14 sec

Could you please explain the later statement. " You time result is better
than the general system result
of 11 min 14 sec" what does it mean? general systemresult? chetan2u @sayantc2k Bunuel

Could you please post the screenshot? Thank you.
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24 Aug 2018, 06:58
Bunuel wrote:
02 min 11 sec
than the general system result
of 11 min 14 sec

Could you please explain the later statement. " You time result is better
than the general system result
of 11 min 14 sec" what does it mean? general systemresult? chetan2u @sayantc2k Bunuel

Could you please post the screenshot? Thank you.

i found this analysis in "question stats" next to "show explanation"Could you please also explain " the average time incorrect and average tme correct " because on forum the average time is different. Also the above mentioned doubt regarding the general system result . Bunuel
>> !!!

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M31-35 &nbs [#permalink] 24 Aug 2018, 06:58
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# M31-35

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