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• ### $450 Tuition Credit & Official CAT Packs FREE November 15, 2018 November 15, 2018 10:00 PM MST 11:00 PM MST EMPOWERgmat is giving away the complete Official GMAT Exam Pack collection worth$100 with the 3 Month Pack ($299) # If xy is not equal to 0, is xy = 70?  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics Author Message TAGS: ### Hide Tags Manager Joined: 21 May 2011 Posts: 208 If xy is not equal to 0, is xy = 70? [#permalink] ### Show Tags Updated on: 11 Jul 2013, 01:03 4 3 00:00 Difficulty: 75% (hard) Question Stats: 49% (01:41) correct 51% (01:32) wrong based on 116 sessions ### HideShow timer Statistics If xy is not equal to 0, is xy = 70? (1) x > y (2) x^2 = y^2 Originally posted by bschool83 on 07 Aug 2011, 09:36. Last edited by Bunuel on 11 Jul 2013, 01:03, edited 1 time in total. Added the OA. Manager Joined: 14 Mar 2011 Posts: 192 Re: DS-700 level-inequality [#permalink] ### Show Tags 07 Aug 2011, 10:01 1 bschool83 wrote: If xy is not equal to 0, is xy = 70? (1) x > y (2) x^2 = y^2 Statement 1 is insufficient as values of x and y are not given Statement 2 is insufficient too. if x^2 = Y^2 then |x| = |y| if x and y are equal to root 70 then xy will be 70. But if anything else then not. Combining statement 1 and 2 we get sufficient answer that xy is not equal to 70. statement one tells that x is greater than y and statement 2 tells that x has same absolute value as y. so x = -Y. In that case xy must be negative. so answer ( C ) If my answer is wrong then please correct it and please provide the OA and correct explanation. Senior Manager Joined: 24 Mar 2011 Posts: 370 Location: Texas Re: DS-700 level-inequality [#permalink] ### Show Tags 07 Aug 2011, 10:19 great question. Agree with C. B is not sufficient alone, since X, Y are not specified as integers. also as per A and B, X can be 8.4 and Y can be -8.4. But then XY = -70 Manager Joined: 16 May 2011 Posts: 189 Concentration: Finance, Real Estate GMAT Date: 12-27-2011 WE: Law (Law) Re: DS-700 level-inequality [#permalink] ### Show Tags 07 Aug 2011, 10:19 S1 x=70 y=1 yes. x=3 y=1 no S2 X=ROOT 70 Y=ROOT 70 YES (x^2=y^2=70). X=9 Y=9 NO (x^2=y^2=81) combined: [x]=[y] and x>y means that x must be positive and y negative. Pos*Neg=Neg hence xy will never be 70. so C Retired Moderator Joined: 18 Sep 2014 Posts: 1128 Location: India If xy is not equal to 0, is xy = 70? [#permalink] ### Show Tags 04 Mar 2016, 04:01 1 If $$xy\neq{0}$$, is $$xy = 70$$? (1) $$x > y$$ (2) $$x^2 = y^2$$ OE Attachment: 21oe.png [ 279.09 KiB | Viewed 2031 times ] CEO Joined: 20 Mar 2014 Posts: 2635 Concentration: Finance, Strategy Schools: Kellogg '18 (M) GMAT 1: 750 Q49 V44 GPA: 3.7 WE: Engineering (Aerospace and Defense) If xy is not equal to 0, is xy = 70? [#permalink] ### Show Tags Updated on: 04 Mar 2016, 04:32 Nevernevergiveup wrote: If $$xy\neq{0}$$, is $$xy = 70$$? (1) $$x > y$$ (2) $$x^2 = y^2$$ Given xy \neq 0, is xy=70? Per statement 1, x>y ---> not sufficient. Per statement 2, x^2=y^2 ----> yes to the question if $$x=y=\sqrt{70}$$ but no if x=y=any other number! Combining, if $$y=-\sqrt{70}$$, $$x =\sqrt{70}$$, and clearly you can see that $$x= \pm y$$ ---> you will never get $$xy = 70$$ (a positive value!). Hence C is the correct answer. Hope this helps. Originally posted by ENGRTOMBA2018 on 04 Mar 2016, 04:14. Last edited by ENGRTOMBA2018 on 04 Mar 2016, 04:32, edited 2 times in total. Edited the solution. Manager Joined: 28 May 2015 Posts: 50 Location: India Concentration: Operations, Strategy GMAT 1: 720 Q50 V38 GPA: 3 WE: Engineering (Manufacturing) Re: If xy is not equal to 0, is xy = 70? [#permalink] ### Show Tags 06 Mar 2016, 01:49 Answer would be C Because x>y is not sufficient. X^2=Y^2=> X=±Y Not sufficient But by combining both A and B, we can conclude X=-Y. So, xy≠positive number 70, xy will always be negative. So C Sent from my Mi 4i using Tapatalk Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 6497 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: If xy is not equal to 0, is xy = 70? [#permalink] ### Show Tags 06 Mar 2016, 03:02 Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution. If xy is not equal to 0, is xy = 70? (1) x > y (2) x^2 = y^2 In the original condition, there are 2 variables(x,y), which should match with the number of equations. So you need 2 equations. For 1) 1 equation, for 2) 1 equation, which is likely to make C the answer. When 1) & 2), x=y or x=-y -> x>y, which makes x=-y. In this case, xy<0 is derived and xy is not 70, which is no and sufficient. Thus, C is the answer.  For cases where we need 2 more equations, such as original conditions with “2 variables”, or “3 variables and 1 equation”, or “4 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 70% chance that C is the answer, while E has 25% chance. These two are the majority. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since C is most likely to be the answer using 1) and 2) separately according to DS definition (It saves us time). Obviously there may be cases where the answer is A, B, D or E. _________________ MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. "Only$99 for 3 month Online Course"
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If xy is not equal to 0, is xy = 70?  [#permalink]

### Show Tags

15 Nov 2016, 06:40
bschool83 wrote:
If xy is not equal to 0, is xy = 70?

(1) x > y

(2) x^2 = y^2

what a tricky one...makes you feel that E is the answer...

1 alone is clearly not sufficient
2 alone says |x| = |y|. don't know anything. x can be+, y can be -, or vice versa, or x=y
different outcomes - not sufficient.

1+2
x>y
so x and y have different signs.
xy must be negative.

sufficient.

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Re: If xy is not equal to 0, is xy = 70?  [#permalink]

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06 Jul 2018, 05:34
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Re: If xy is not equal to 0, is xy = 70? &nbs [#permalink] 06 Jul 2018, 05:34
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