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Tricky Exponents Question

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Tricky Exponents Question

by skalevar » Sun Jul 18, 2010 1:53 pm
I'm not sure how to simplify this problem:

2^x - 2^(x-2) = 3 (2^13)

What is x?

I got the question right by picking answers from the multiple choice answers, but there should have been a better way to solve. Please let me know if you have any insights.



(Correct answer is 15)
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by Stuart@KaplanGMAT » Sun Jul 18, 2010 1:59 pm
Hi!

Like a lot of the questions you'll find from reputable sources, this one has been discussed a few times. You can find one such discussion at:

https://www.beatthegmat.com/exponent-pro ... 17726.html

The search function is very helpful - I did a search on "3(2^13)" and found the post immediately.

Good luck!
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by Stuart@KaplanGMAT » Sun Jul 18, 2010 2:00 pm
skalevar wrote:I'm not sure how to simplify this problem:

2^x - 2^(x-2) = 3 (2^13)

What is x?

I got the question right by picking answers from the multiple choice answers, but there should have been a better way to solve. Please let me know if you have any insights.



(Correct answer is 15)
As an aside, as you note in your own post, answer choices are extremely helpful in finding the best solution to a problem. Accordingly, you should always include the choices when you post a question.

Also, if you know it, please include the source of the question.
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by skalevar » Sun Jul 18, 2010 6:46 pm
The source of the question is the Practice Test 1 from mba.com. (simulated CAT test)

The answer choices were:
A. 9
B. 11
C. 13
D. 15
E. 17

Thanks for your help!
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