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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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19 Dec 2015, 13:39
Hi Bunnel It might sound lame, but why do we need to consider 2 cases for statement 1? Why can we not simply consider x= zy which means z>y while we are testing for whether y>equal to Z and hence statement 1 is sufficient.



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Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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20 Oct 2016, 11:29
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yashrakhiani wrote: IS x = y z??
1)x+ y = z
2)x<0 Answer is C. From the question, if x>0, x = yz if x<0, x = (yz) = zy Let's start with the easy statement  Statement 2. (2): Insufficient x<0 doesn't give us any information about y and z. Eliminate B and D (1): Insufficient Statement 1 says that x = z  y If x<0 , then the answer is yes since x will be equal to yz if x>0, then the answer is no since x = zy We have a Yes and a No. Eliminate A. (1) and (2) together: Sufficient We have x<0 and x = z  y. hence, x = yz  Need 3 Kudos
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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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28 Oct 2016, 23:19
I have a doubt here. if we see, if x is +ve then x=yz and if x is ve x+y = z.
st 1 says x+y = z , so why cant A be suff



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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29 Oct 2016, 00:41



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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29 Oct 2016, 01:04
per st 1, when x + y = z, this will happen when x<=0, so this st is sufficient. as when x<=0, then x=yz where am i going wrong or am confusing some concept



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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01 Nov 2016, 08:02
Bunuel : Is mod x = yz I interpreted the question as " Is x = +(yz) or x= (y z)?" And hence, since the first option mentions x = y+z, i chose A. Am i missing something?



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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01 Nov 2016, 12:36
Tricky, but doable:
(1) x+y = z
Ex 1: 2+3=1 > 31=2 > works *
Ex 2: 3+(2)=1 = > 21=3 > fail (we don't get absolute value)
Ex 3: 3+5=8 > 58=3 > fail
We can see a pattern from Ex 2 and 3 that x must be negative in order for this to work.
NOT SUFFICIENT
(2) x<0 > NOT SUFFICIENT by itself
(1)+(2) > SUFFICIENT



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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08 Feb 2017, 20:52
EvaJager wrote: sayak636 wrote: Is X= Y Z?
1. X+Y= Z 2. X< 0 (1) Can be rewritten as X = Y + Z, so X = Y + Z, which would be equal to Y  Z, if and only if \(Y+Z\leq0\). Obviously, we don't know that, so (1) insufficient. (2) Cannot be sufficient, it doesn't say anything about Y and Z. (1) and (2) together: X = Y + Z < 0, therefore X = Y  Z, sufficient. Answer: C Hello Eva, Can you please explain how do you reach to below conclusion : "(1) and (2) together: X = Y + Z < 0, therefore X = Y  Z, sufficient."
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Is x = y  z? [#permalink]
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06 Mar 2017, 19:19
sitagupta385 wrote: Is x = y  z?
1) x + y = z 2) x < 0 is x= yz && x= zy ?? (1) x= zy ...but we dont know whether x= yz.. insuff (2) x<0 so x= zy but we dont know x= yz or not.. insuff combining we know x= yz (from 1) && x= yz(from2) thus x = y  z suff Ans C



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Re: Is x = y  z? [#permalink]
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06 Mar 2017, 20:21
1. X+Y=Z x=yz x=yz Ans a. Hit kudos if i this solution is ryt. Sent from my MotoG3 using GMAT Club Forum mobile app



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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07 Mar 2017, 22:56
Bunuel , i have one doubt in this question. i have gone through the explanations in chain, still not clear. suppose we have been asked in question ... is x=1 ? according to explanations it says x=1 && x=1 ? A) x=1 .... so this must be insufficient. please correct me if I am missing anything.



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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08 Mar 2017, 00:21



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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08 Mar 2017, 05:17
St 1: yz = x. if x is positive x = zy. if x is negative, x = yz. INSUFFICIENT St 2: x is negative. no idea about y and z. INSUFFICIENT
St 1 & St 2: yz = x. x is negative. hence x = yz. ANSWER
Option C



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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08 Mar 2017, 12:26
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Bunuel wrote: mbaprep2016 wrote: Bunuel , i have one doubt in this question. i have gone through the explanations in chain, still not clear. suppose we have been asked in question ... is x=1 ? according to explanations it says x=1 && x=1 ? A) x=1 .... so this must be insufficient. please correct me if I am missing anything. So, the question is: Does x = 1? (1) x = 1. This would be sufficient because 1 = 1 and we would have a definite YES answer to the question. Hope it helps. I am sorry for asking same question again and again but with similar logic Question : Is x = y  z? when x > 0 x= yz && when x<0 x= zy ?? we have to choose between two values Now A says x= zy... this clearly indicates x<0 ...hence sufficient



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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09 Mar 2017, 00:04
mbaprep2016 wrote: Bunuel wrote: mbaprep2016 wrote: Bunuel , i have one doubt in this question. i have gone through the explanations in chain, still not clear. suppose we have been asked in question ... is x=1 ? according to explanations it says x=1 && x=1 ? A) x=1 .... so this must be insufficient. please correct me if I am missing anything. So, the question is: Does x = 1? (1) x = 1. This would be sufficient because 1 = 1 and we would have a definite YES answer to the question. Hope it helps. I am sorry for asking same question again and again but with similar logic Question : Is x = y  z? when x > 0 x= yz && when x<0 x= zy ?? we have to choose between two values Now A says x= zy... this clearly indicates x<0 ...hence sufficient OK. Let me demonstrate with number plugging. For (1) if x = 1, and y =2 and z=3, x does not equal to y  z.
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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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25 Apr 2017, 23:09
Hi Bunuel, Please point out the error in my approach. x= y  z. So, when x<0, x=yz => x = z  y(1) x>0, x = y  zStatement 1. x = z  y, which is same as (1). So is A not the answer ?



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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29 Jul 2017, 18:06
Bunuel wrote: Is \(x=yz\)?
Note that \(yz\) must be \(\geq{0}\), because absolute value (in our case \(x\)) can not be negative.
Generally question asks whether \(yz\geq{0}\) and whether the difference between them equals to \(x\).
(1) \(x=yz\) if \(x>0\) > \(yz\) is negative > no good for us; if \(x\leq{0}\) > \(yz\) is positive > good. Two possible answers not sufficient;
(2) \(x<0\) Not sufficient (we need to know value of yz is equal or not to x)
(1)+(2) Sufficient.
Answer: C. Just to make this good answer a little clearer. An absolute value cannot equal a negative value. Therefore x=yz. as shown in expression 1. If X>0 then we have 5 (because there is a neg sign in front so X = positive 5 but the expression is 5) = yz. But if Yz = 5 that means x = 5 which is not possible! As said above an absolute value has to equal a positive number. So if X<0 then X could be 5 and  * 5 is positive 5. So yz = 5 and therefore together we can say that X=YZ



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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13 Aug 2017, 18:30
So absolute value we have x = yz or –x = yz . That's how you rewrite the ABS value equation. You write one equation with positive X and one with negative to cover both sides.
1) Tells us X+Y=z . It can be arranged into –x=Yz which matches one of our absolute value formulas. However, if X is positive yz would be negative and then YZ couldn’t equal the absolute value since the ABS value has to equal a non negative numbers.
2) X<0 but we know nothing about Y or Z
3) Combined now we know –(negative number) is positive therefore YZ must be positive = Therefore we know x = y  z ?



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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31 Aug 2017, 08:54
Bunuel wrote: Is \(x=yz\)?
Note that \(yz\) must be \(\geq{0}\), because absolute value (in our case \(x\)) can not be negative.
Generally question asks whether \(yz\geq{0}\) and whether the difference between them equals to \(x\).
(1) \(x=yz\) if \(x>0\) > \(yz\) is negative > no good for us; if \(x\leq{0}\) > \(yz\) is positive > good. Two possible answers not sufficient;
(2) \(x<0\) Not sufficient (we need to know value of yz is equal or not to x)
(1)+(2) Sufficient.
Answer: C. Bunuel, thanks for your explanation. However, I tried solving this testing cases and I feel like i proved found a case where st1&2 don't hold. Can someone help me out please? 1) x+y=z 2)x<0 Let's say x=4, y=3, z=1 4 +3=1 l4l does not equal 31 (i.e. lxl does not equal yz. However, if you use 2,5,&3 then it does work. Hence, shouldn't it be E?



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Re: Is x = y  z ? (1) x + y = z (2) x < 0 [#permalink]
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31 Aug 2017, 08:57
brandon7 wrote: Bunuel wrote: Is \(x=yz\)?
Note that \(yz\) must be \(\geq{0}\), because absolute value (in our case \(x\)) can not be negative.
Generally question asks whether \(yz\geq{0}\) and whether the difference between them equals to \(x\).
(1) \(x=yz\) if \(x>0\) > \(yz\) is negative > no good for us; if \(x\leq{0}\) > \(yz\) is positive > good. Two possible answers not sufficient;
(2) \(x<0\) Not sufficient (we need to know value of yz is equal or not to x)
(1)+(2) Sufficient.
Answer: C. Bunuel, thanks for your explanation. However, I tried solving this testing cases and I feel like i proved found a case where st1&2 don't hold. Can someone help me out please? 1) x+y=z 2)x<0 Let's say x=4, y=3, z=1 4 +3=1l4l does not equal 31 (i.e. lxl does not equal yz. However, if you use 2,5,&3 then it does work. Hence, shouldn't it be E? x=4, y=3, z=1 does not satisfy the first statement.
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