Hi everyone,
This forum has been a fantastic source of information for me and I just want to thank everyone for their helpful posts.
I'm reviewing my first GMAT PREP CAT but i'm stumped on how to solve this question.
if 2^x - 2^(x-2) = 3* (2^13), what is x?
can anyone offer some enlightenment?
answer: 15
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exponent problem
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walkingbanana
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gaggleofgirls
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2^x - 2^(x-2) can only be dealt with by factoring....
= 2^(x-2) * (2^2 - 1) becuase 2^2 * 2(x-2) = 2^2+x-2 = 2^x
= 2^(x-2) (4-1)
= 2^(x-2) * 3
SO
2^(x-2) * 3 = 3 * 2^13
2^(x-2) = 2^13
x-2 = 13
x = 15
-Carrie
= 2^(x-2) * (2^2 - 1) becuase 2^2 * 2(x-2) = 2^2+x-2 = 2^x
= 2^(x-2) (4-1)
= 2^(x-2) * 3
SO
2^(x-2) * 3 = 3 * 2^13
2^(x-2) = 2^13
x-2 = 13
x = 15
-Carrie
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walkingbanana
- Junior | Next Rank: 30 Posts
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- Joined: Tue Jan 27, 2009 8:35 pm
- Location: Los Angeles, CA
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