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What is the value of x ? [#permalink]
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07 Oct 2011, 23:39
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What is the value of \(x\) ? (1) \(x = x\) (2) \(x^2 = 4\)
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08 Oct 2011, 22:03
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siddhans wrote: What is the value of x? (1) x = –x (2) \(x^2\) = 4 Sorry but i am having a hard time understanding whats going on here and have got more confused... x=1; x=1; x=1; x<>x; So, x can't be 1. x=2; x=2=2; x=2; So, x=x; x can be 2. These 2 above statements confused me a lot... if x=2 ; whats the reason for doing this step x = 2? and then x =2 ?? What is modulus OR ? If a variable is ve, and we wrap it around with , it becomes +ve. If a variable is +ve, and we wrap it around with , it remains +ve. If a variable is 0, and we wrap it around with , it remains 0. So, 2; Wrap it around; 2=2 +2; Wrap it around; +2=+2=2 0; Wrap it around; 0=0 Statement 1: (1) x = –x Let's say x=1; L.H.S.=x=1 R.H.S.=x=1=1 We know; 1 <> 1, so the expression x=x doesn't hold good for x=1; And it won't hold good for any +ve number. Now, let's say x=1; L.H.S.=x=1 R.H.S.=x=1=1 We know; 1 = 1, so the expression x=x does indeed hold good for x=1; And it will hold good for any ve number. For x=0.464654 OR x=100000; this expression will hold good. Thus, we won't be able to find a conclusive value for x. Not Sufficient.
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Re: What is the value of x ? [#permalink]
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07 Oct 2011, 23:44
siddhans wrote: Searched for this multiple times before posting but couldnt find it...
What is the value of x ? (1) x = –x (2) \(x^2\) = 4 Its B st1: X= X It tells us that X is negative . Nothing about the value of X.. hence insufficient St2: X^2 = 4 this can be writen as x= 2 hence sufficient .



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Re: What is the value of x ? [#permalink]
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08 Oct 2011, 00:43
sudhir18n wrote: siddhans wrote: Searched for this multiple times before posting but couldnt find it...
What is the value of x ? (1) x = –x (2) \(x^2\) = 4 Its B st1: X= X It tells us that X is negative . Nothing about the value of X.. hence insufficient St2: X^2 = 4 this can be writen as x= 2 hence sufficient . Hi Sudhir, For st1 When its given x = X does that mean we need to transfer the negative sign on the other side since we need to find what x is ? x = x ? but x is positive or 0 , right? so x = 0 / +ve  hence insufficient ? is this correct?



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08 Oct 2011, 01:07
siddhans wrote: Hi Sudhir,
For st1
When its given x = X
does that mean we need to transfer the negative sign on the other side since we need to find what x is ? x = x ?
but x is positive or 0 , right? so x = 0 / +ve  hence insufficient ? is this correct?
Statement 1 just means that x is negative. e.g. x=5 & x=x=>x=5 x=10000 & x=x=>x=10000 We can't determine the value of x or x So, yes what you said is corrected.
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Re: What is the value of x ? [#permalink]
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08 Oct 2011, 01:10
blink005 wrote: siddhans wrote: Hi Sudhir,
For st1
When its given x = X
does that mean we need to transfer the negative sign on the other side since we need to find what x is ? x = x ?
but x is positive or 0 , right? so x = 0 / +ve  hence insufficient ? is this correct?
Statement 1 just means that x is negative. e.g. x=5 & x=x=>x=5 x=10000 & x=x=>x=10000 We can't determine the value of x or x So, yes what you said is corrected. why are we finding value of x? we are asked to find x...i am not sure why did you find x in the examples above.???



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08 Oct 2011, 01:15
My point was to tell you that statement 1 is insufficient. I just tried to highlight different values of x and their relations. Nothing else.
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Re: What is the value of x ? [#permalink]
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08 Oct 2011, 01:18
siddhans wrote: Searched for this multiple times before posting but couldnt find it...
What is the value of x ? (1) x = –x (2) \(x^2\) = 4 It is not mandatory to solve it algebraically. I have seen modulus question can be solved using PIN quite well. Here, Say; x=0; x=0; x=0; x=x; So, x can be 0. x=1; x=1; x=1; x<>x; So, x can't be 1. x=2; x=2; x=2; x<>x; So, x can't be 2. We see that the modulus of a +ve number is always +ve. When we flip the sign of it we get a ve. Thus, x can't be +ve because a +ve will not be equal to ve. x=2; x=2=2; x=2; So, x=x; x can be 2. x=3; x=3=3; x=3; So, x=x; x can be 3. In fact x can be any ve number. x <= 0 AND x >= 0 Not Sufficient. 2) x^2=4 x=+2 So, x=2=2 Or x=+2=2 Either way, x=2 Sufficient. Ans: "B"
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Re: What is the value of x ? [#permalink]
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08 Oct 2011, 11:01
@fluke  crisp explanation. thx.
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Re: What is the value of x ? [#permalink]
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08 Oct 2011, 21:10
fluke wrote: siddhans wrote: Searched for this multiple times before posting but couldnt find it...
What is the value of x ? (1) x = –x (2) \(x^2\) = 4 It is not mandatory to solve it algebraically. I have seen modulus question can be solved using PIN quite well. Here, Say; x=0; x=0; x=0; x=x; So, x can be 0. x=1; x=1; x=1; x<>x; So, x can't be 1. x=2; x=2; x=2; x<>x; So, x can't be 2. We see that the modulus of a +ve number is always +ve. When we flip the sign of it we get a ve. Thus, x can't be +ve because a +ve will not be equal to ve. x=2; x=2=2; x=2; So, x=x; x can be 2. x=3; x=3=3; x=3; So, x=x; x can be 3. In fact x can be any ve number. x <= 0 AND x >= 0 Not Sufficient. 2) x^2=4 x=+2 So, x=2=2 Or x=+2=2 Either way, x=2 Sufficient. Ans: "B" Sorry but i am having a hard time understanding whats going on here and have got more confused...



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Re: What is the value of x ? [#permalink]
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08 Oct 2011, 21:13
fluke wrote: siddhans wrote: Searched for this multiple times before posting but couldnt find it...
What is the value of x ? (1) x = –x (2) \(x^2\) = 4 It is not mandatory to solve it algebraically. I have seen modulus question can be solved using PIN quite well. Here, Say; x=0; x=0; x=0; x=x; So, x can be 0. x=1; x=1; x=1; x<>x; So, x can't be 1. x=2; x=2; x=2; x<>x; So, x can't be 2. We see that the modulus of a +ve number is always +ve. When we flip the sign of it we get a ve. Thus, x can't be +ve because a +ve will not be equal to ve. x=2; x=2=2; x=2; So, x=x; x can be 2. x=3; x=3=3; x=3; So, x=x; x can be 3. In fact x can be any ve number. x <= 0 AND x >= 0 Not Sufficient. 2) x^2=4 x=+2 So, x=2=2 Or x=+2=2 Either way, x=2 Sufficient. Ans: "B" Sorry but i am having a hard time understanding whats going on here and have got more confused... x=1; x=1; x=1; x<>x; So, x can't be 1. x=2; x=2=2; x=2; So, x=x; x can be 2. These 2 above statements confused me a lot... if x=2 ; whats the reason for doing this step x = 2? and then x =2 ??



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Re: What is the value of x ? [#permalink]
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08 Oct 2011, 22:41
fluke wrote: siddhans wrote: What is the value of x? (1) x = –x (2) \(x^2\) = 4 Sorry but i am having a hard time understanding whats going on here and have got more confused... x=1; x=1; x=1; x<>x; So, x can't be 1. x=2; x=2=2; x=2; So, x=x; x can be 2. These 2 above statements confused me a lot... if x=2 ; whats the reason for doing this step x = 2? and then x =2 ?? What is modulus OR ? If a variable is ve, and we wrap it around with , it becomes +ve. If a variable is +ve, and we wrap it around with , it remains +ve. If a variable is 0, and we wrap it around with , it remains 0. So, 2; Wrap it around; 2=2 +2; Wrap it around; +2=+2=2 0; Wrap it around; 0=0 Statement 1: (1) x = –x Let's say x=1; L.H.S.=x=1 R.H.S.=x=1=1 We know; 1 <> 1, so the expression x=x doesn't hold good for x=1; And it won't hold good for any +ve number. Now, let's say x=1; L.H.S.=x=1 R.H.S.=x=1=1 We know; 1 = 1, so the expression x=x does indeed hold good for x=1; And it will hold good for any ve number. For x=0.464654 OR x=100000; this expression will hold good. Thus, we won't be able to find a conclusive value for x. Not Sufficient. Thats a great explnation!!!... I knew what modulus is but confused on the cases you had mentioned earlier... Do you know how can we do this algebrically too? Just curious to know



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Re: What is the value of x ? [#permalink]
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09 Oct 2011, 10:01
38 Secs to figure its B :D
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Re: What is the value of x ? [#permalink]
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10 Oct 2011, 06:08
Ans is B. Question asks for the value of x
Statement 2) gives us +2 and since we need the absolute value... therefore we can only get 2. Sufficient



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11 Oct 2011, 04:29
siddhans wrote: Searched for this multiple times before posting but couldnt find it...
What is the value of x ? (1) x = –x (2) \(x^2\) = 4 Using statement 1 : We cannot find the value of x Using statement two we know x= + 2...so x is always 2. Hence sufficient. So answer is B.
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Re: What is the value of x ? [#permalink]
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11 Oct 2011, 16:37
x=?
1. Not sufficient x= x
=> x = x
without knowing x, we cannot saying anything about x.
all we know from the given expression that x is ve
=> x can be 1 or 2..and they all have different x values.
2. Sufficient
x^2= 4
=> x=2
Answer is B.



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12 Oct 2011, 11:41



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18 Oct 2011, 23:11
+B fluke and others, just want to know if this question is really of 600 to 700 level ? or sub 600 level ?



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Re: What is the value of x ? [#permalink]
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24 Oct 2011, 02:17
Spidy001 wrote: x=?
1. Not sufficient x= x
=> x = x
without knowing x, we cannot saying anything about x.
all we know from the given expression that x is ve
=> x can be 1 or 2..and they all have different x values.
2. Sufficient
x^2= 4
=> x=2
Answer is B. Can someone explain whats wrong with this method ? 1) x = x this x =  (x) or x =  (+x) since x can be +ve pr ve thus x = x or x = x x  x = 0 or x + x = 0 0=0 or 2x = 0 x =0....



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Re: What is the value of x ? [#permalink]
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24 Oct 2011, 06:39
siddhans wrote: :( Can someone explain whats wrong with this method ? 1) x = x this x =  (x) or x =  (+x) since x can be +ve pr ve thus x = x or x = x x  x = 0 or x + x = 0 0=0 or 2x = 0 x =0.... x can't be negative. Absolute value of a number is always nonnegative. Do you follow?




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