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Can someone explain this math problem?

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Guest
 Post subject: Can someone explain this math problem?
 Post Posted: Thu Feb 14, 2008 11:54 am 
[deleted b/c poster did not cite author]
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Guest
 Post subject:
 Post Posted: Thu Feb 14, 2008 4:18 pm 
it's the result of factoring: 2^x + 2^x = 2^x(1+1) = 2^x(2)

hope this helps.
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rohit801
 Post subject: clarify
 Post Posted: Sat Feb 16, 2008 6:00 pm 
[deleted b/c poster did not cite author]

look at it this way: it is clear that X + X = 2X, right- u are adding the same thing two times, so it is 2 times that thing.
in this case the expression is 2^X and that is being added twice, right? so, it becomes 2 * 2 ^x.
Now, 2 means 2^1 [2^2=4 etc]. now, we have 2^1 * 2 ^x. what do we see here- same BASE [2] being multiplied with exponents. so, we can ADD the powers [just as we can SUBTRACT the exponents when division is concerned]. so, it becomes BASE ^ [add exponenets] = 2 ^ x+1.

does that help?
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StaceyKoprince
 Post subject:
 Post Posted: Thu Feb 21, 2008 10:49 pm 
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ManhattanGMAT Staff


Posts: 6064
Location: San Francisco
please cite the source of this problem; if you don't, we will have to delete it (and we also won't answer it, obviously!)

please don't forget to cite sources in this folder guys!

_________________
Stacey Koprince
Instructor
Director of Online Community
ManhattanGMAT
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Guest
 Post subject: Re: Can someone explain this math problem?
 Post Posted: Wed Feb 27, 2008 5:23 pm 
[deleted b/c poster did not cite author]


If 2^x=A then A+A=2A

So:
2(2^x)
-------------
2^y


It can be rewritten as:

(2^1)(2^x)
---------------
2^y

With exponents with the same base, when you divide them you keep the base and subtract the exponents, and when you multiply them you add the exponents.

So we now have:

2^(x+1)
------------
2^y


And then we take the bottom part of the equation with the SAME BASE and incorporate it in the top:

1/(2^y) is the same as 2^-y


We can multiply 2^(x+1) and 2^-y

And we get 2^x-y+1
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