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Joined: 29 May 2017
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Re M0232 [#permalink]
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30 May 2017, 05:59
I think this is a poorquality question and I don't agree with the explanation. The question asks the value of x^2. Why do we calculate x and then x^2. If X^2 is the value required, both statements independently be sufficient.



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Re: M0232 [#permalink]
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30 May 2017, 08:06



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Re M0232 [#permalink]
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17 Jul 2017, 02:21
I don't agree with the explanation. the answer should be D .If we divide both sides of the 2nd equation with x^2 , we are left with 1=x , thus x^=1



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Re: M0232 [#permalink]
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17 Jul 2017, 02:29
Arjun17 wrote: I don't agree with the explanation. the answer should be D .If we divide both sides of the 2nd equation with x^2 , we are left with 1=x , thus x^=1 It's always better to read the whole discussion before posting a question. You are making a rookie mistake, which is addressed in a post just above yours. You cannot divide x^2 = x^3 by x^2 because x^2 could be 0 and we cannot divide by 0. By doing so, you are loosing a root, namely x = 0 (notice that both x = 0 and x = 1 satisfy x^2 = x^3, and this is clearly shown in the original solution). Takeaway: never reduce equation by variable (or expression with variable), if you are not certain that variable (or expression with variable) doesn't equal to zero. We cannot divide by zero.
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Re: M0232 [#permalink]
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03 Oct 2017, 11:27
Bunuel,
Can you please throw some light on my query.
For statement 2: I made till this point \(x^2\) (1−x)=0  > eq 1
When I segregated \(x^2\) = 0 and (1x) = 0. Since \(x^2\) is always +ve and can't be 0 , so I eliminated this part. Finally, got x = 1.
I have seen such type of questions,even though when \(x^2\) is 0 some times \(x^2\) taken +ve and in few solutions it is not( case in our question). Under what cases we need to consider +ve or 0 when we have such eq 1 type.



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Re: M0232 [#permalink]
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03 Oct 2017, 11:30



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Joined: 27 Oct 2017
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Quick question, from 1, because we are not given x=/= 0 in the stem, we know we can square the equation because 0 =/= (1)^(1/2), b/c we cannot take root of 1, is that correct? Is there a general way to check whether we are able to perform operations on variables in equations and inequalities? Thanks in advance.



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Re: M0232 [#permalink]
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31 Oct 2017, 21:10
alekkx wrote: Quick question, from 1, because we are not given x=/= 0 in the stem, we know we can square the equation because 0 =/= (1)^(1/2), b/c we cannot take root of 1, is that correct? Is there a general way to check whether we are able to perform operations on variables in equations and inequalities? Thanks in advance. Check : Manipulating Inequalities (adding, subtracting, squaring etc.). For more check Ultimate GMAT Quantitative Megathread
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New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics







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