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# What is the value of x?

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Math Revolution GMAT Instructor
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What is the value of x? [#permalink]

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27 Nov 2017, 00:07
00:00

Difficulty:

65% (hard)

Question Stats:

43% (00:57) correct 57% (00:44) wrong based on 58 sessions

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[GMAT math practice question]

What is the value of $$x$$?

1) $$x^{2x}=1$$
2) $$x^x=1$$
[Reveal] Spoiler: OA

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Re: What is the value of x? [#permalink]

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27 Nov 2017, 00:10
MathRevolution wrote:
[GMAT math practice question]

What is the value of $$x$$?

1) $$x^{2x}=1$$
2) $$x^x=1$$

This is a copy of the following question: https://gmatclub.com/forum/what-is-the- ... 51809.html
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Re: What is the value of x? [#permalink]

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27 Nov 2017, 16:43
Isn't 0^0 also equal to 1?

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Re: What is the value of x? [#permalink]

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27 Nov 2017, 17:37
kimiah39 wrote:
Isn't 0^0 also equal to 1?

Hi..

there are various schools of thought ....
But I would say it is undefined and at the best, controversial with values as 0,1 or undefined..

why it should not be 1..
$$0^0 = 0^{a-a}=0^a*0^{-a}=\frac{0^a}{0^a}=\frac{0}{0}$$

But anything divided by 0 is undefined
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Absolute modulus :http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

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Re: What is the value of x? [#permalink]

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27 Nov 2017, 20:08
kimiah39 wrote:
Isn't 0^0 also equal to 1?

0^0, in some sources equals to 1 (not 0), some mathematicians say it's undefined. But you won't need this for the GMAT because the case of 0^0 is not tested on the GMAT.

Real GMAT question would rule out this possibility by saying that $$x \neq 0$$
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Re: What is the value of x? [#permalink]

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28 Nov 2017, 23:24
=>

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

Since we have 1 variable (x) and 0 equations, D is most likely to be the answer.

00 lies outside the scope of the GMAT exam.

Condition 1)
There are two possible solutions: x = 1 and x = -1. Since the solution is not unique, this condition is not sufficient.

Condition 2)
We have the unique solution x = 1. Since this solution is unique, this condition is sufficient.

Therefore, the answer is B.

If the original condition includes “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations” etc., one more equation is required to answer the question. If each of conditions 1) and 2) provide an additional equation, there is a 59% chance that D is the answer, a 38% chance that A or B is the answer, and a 3% chance that the answer is C or E. Thus, answer D (conditions 1) and 2), when applied separately, are sufficient to answer the question) is most likely, but there may be cases where the answer is A,B,C or E.
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Re: What is the value of x? [#permalink]

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28 Nov 2017, 23:52
x + 2y = 4 and your welcome :D

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Re: What is the value of x?   [#permalink] 28 Nov 2017, 23:52
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# What is the value of x?

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