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What is the value of x + 7 ?

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What is the value of x + 7 ? [#permalink] New post 13 May 2010, 09:36
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What is the value of │x + 7│?

(1) |x + 3│= 14
(2) (x+2)^2= 169
[Reveal] Spoiler: OA
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Re: Data Sufficiency Problem. [#permalink] New post 13 May 2010, 09:42
ajitsah wrote:
What is the value of │x + 7│?
(1) │x + 3│= 14
(2) (x+2)2 = 169

[Reveal] Spoiler:
OA: D


Am I missing something here. My ans was C.
Stat 1 gives two results; x= 11,-17
Stat 2 gives two results; x= 11,-15

Combining these two, we get that x=11 satisfies the statements and answers the question.
I have read this reasoning somewhere. Pls suggest whether the logic is correct or not, or what should be the strategy behind these type of questions when one variable satisfies both statements and in turn becomes sufficient to answer the question.
Thanks
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Re: Data Sufficiency Problem. [#permalink] New post 13 May 2010, 09:44
ajitsah wrote:
What is the value of │x + 7│?
(1) │x + 3│= 14
(2) (x+2)2 = 169



One unknown, two equations.

Start with either one and you realize there are two possible values.

For (1): 11 and -17
For (2): 11 and -15

Thus each alone are not sufficient (knock off A, B and D).

Put the together and you see 11 is the only outcome in both that is the same.

The answer is C - together sufficient.

Yeah something is wrong with the OA (typo maybe)
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Re: Data Sufficiency Problem. [#permalink] New post 13 May 2010, 09:47
yeah I just had that exact same reaction...

Statement One X = 11 or -17 plugging it back into the equation X+7= 18 or,10 So NS

Statement Two X=11 or -15 plugging it back into the equation X+7 = 18 or 8

X=11 and X+7 is the only solution that is a constant and thus the answer C

There is no way this can be D unless you forgot to include a clause about X>0
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Re: Data Sufficiency Problem. [#permalink] New post 13 May 2010, 23:40
can you please quote the source ..the answer should not be D it should be C


1) x = 11 or x = -17
so |x + 7 | = 18 or x= 10

so 1 is not sufficient ...and if 1 is not sufficient how can the answer be D ??
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What is the value of |x + 7|? [#permalink] New post 18 Aug 2010, 00:49
What is the value of |x + 7|?

(1) |x + 3| = 14
(2) (x + 2)^2 = 169

Last edited by Bunuel on 01 Jul 2014, 09:39, edited 2 times in total.
Edited the OA.
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Re: What is the value of |x + 7|? [#permalink] New post 18 Aug 2010, 11:43
Answer D is correct.

A. gives us two values of x i.e. x = 11 or x = -11. However when you substitute these values back into equation given in A, x = 11 is the only valid value. Hence we can find mod ( x + 7 ) = 18

Hence A sufficient.

B. also gives us two values of x, i.e. 11 and -11. Resubstitute both values and validate the equation given in B. It holds true only for x = 11. Hence we are able to find mod (x + 7).

Hence B is sufficient as well.

Hence D is correct answer. Thank You.

Thanks,
Akhil M.Parekh
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Re: What is the value of |x + 7|? [#permalink] New post 18 Aug 2010, 18:14
amp0201 wrote:
Answer D is correct.

A. gives us two values of x i.e. x = 11 or x = -11. However when you substitute these values back into equation given in A, x = 11 is the only valid value. Hence we can find mod ( x + 7 ) = 18

Hence A sufficient.

B. also gives us two values of x, i.e. 11 and -11. Resubstitute both values and validate the equation given in B. It holds true only for x = 11. Hence we are able to find mod (x + 7).

Hence B is sufficient as well.

Hence D is correct answer. Thank You.


Thanks,
Akhil M.Parekh



B gives 2 values as 11 and -15

(x+2)^2= 13 ^2

(x+2)=+-13

x=11 , -15

Hence 2 different values

Can you explain how did you get values as 11 and -11 in statement B?
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Re: What is the value of |x + 7|? [#permalink] New post 18 Aug 2010, 20:15
amp0201 wrote:
Answer D is correct.

A. gives us two values of x i.e. x = 11 or x = -11. However when you substitute these values back into equation given in A, x = 11 is the only valid value. Hence we can find mod ( x + 7 ) = 18

Hence A sufficient.

B. also gives us two values of x, i.e. 11 and -11. Resubstitute both values and validate the equation given in B. It holds true only for x = 11. Hence we are able to find mod (x + 7).

Hence B is sufficient as well.

Hence D is correct answer. Thank You.

Thanks,
Akhil M.Parekh


I think its C.

1) This raises two values, X=11 and -17. Therefore, insufficient.
2) This again raises to two values, X=11 and -15. Therefore, insufficient.

Considering 1 and 2, the common value X=11 is considered. Therefore, sufficient.
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Re: What is the value of |x + 7|? [#permalink] New post 18 Aug 2010, 21:11
Sorry my bad. Yes I calculated it wrong.

For B - it is 11 and -15. Hence insufficient.

Together A and B -> x = 11. Hence C is correct answer.

Thanks for pointing out the mistake.

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Re: What is the value of |x + 7|? [#permalink] New post 03 Sep 2010, 09:40
Answer must be C.

Statement (1) gives two values, x = 11, and x = -17. Both of these values adequately satisfy the equation |x+3|=14. Plug them into |x+7| to get |11+7|=18 and |-17+7|=10. Two different values, thus we can't determine a single solution for x.

Statement (2) also gives two values, x = 11 and x = -15. Both of these values satisfy the equation (x+2)^2=169. Plug them into |x+7| to get |11+7|=18 and |-15+7|=8. Two different values again, thus we can't determine a single solution for x.

Combine (1) and (2) to get x = 11, which results in a single value for |x+7|.
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Re: What is the value of |x + 7|? [#permalink] New post 03 Sep 2010, 22:37
I think D is wrong. What do you think ?
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What is the value of |x + 7|? [#permalink] New post 09 Sep 2010, 10:47
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What is the value of |x + 7|?

(1) |x+3|=14 --> x=11 or x=-17, so |x+7|=18 or |x+7|=10. Not sufficient.

(2) (x+2)^2=169 --> x=11 or x=-15, so |x+7|=18 or |x+7|=8. Not sufficient.

(1)+(2) |x+7|=18. Sufficient.

Answer: C.
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Re: Data Sufficiency Problem. [#permalink] New post 08 Nov 2010, 05:59
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I've changed OA in the first post. It's clearly C.
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Re: What is the value of x + 7 ? [#permalink] New post 01 Jul 2014, 09:06
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Re: What is the value of x + 7 ?   [#permalink] 01 Jul 2014, 09:06
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