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[5 ^ k] - [5 ^ (k-1)]

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Senior Manager
Senior Manager
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Joined: 05 Oct 2008
Posts: 268

Kudos [?]: 557 [0], given: 22

[5 ^ k] - [5 ^ (k-1)] [#permalink]

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New post 16 Nov 2008, 09:19
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

How do you solve for this?

[5 ^ k] - [5 ^ (k-1)]

Do not have the AC - only have the OA, will post it later.

Last edited by study on 17 Nov 2008, 02:52, edited 1 time in total.

Kudos [?]: 557 [0], given: 22

Current Student
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Joined: 28 Dec 2004
Posts: 3345

Kudos [?]: 325 [0], given: 2

Location: New York City
Schools: Wharton'11 HBS'12
Re: Exponents [#permalink]

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New post 16 Nov 2008, 10:08
study wrote:
How do you solve for this?

5^k - 5 ^k-1

Do not have the AC - only have the OA, will post it later.



5^(k-1)(5-1) =4*5^(k-1)

Kudos [?]: 325 [0], given: 2

Director
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Joined: 14 Aug 2007
Posts: 726

Kudos [?]: 222 [0], given: 0

Re: Exponents [#permalink]

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New post 17 Nov 2008, 00:56
study wrote:
How do you solve for this?

5^k - 5 ^k-1

Do not have the AC - only have the OA, will post it later.


Study,

Can you please put brackets when you post such questions?
Though this problem is pretty straightforward, putting the brackets makes it much easier for folks to understand the problem.
It will also help you to get much faster response.

Kudos [?]: 222 [0], given: 0

Senior Manager
Senior Manager
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Joined: 05 Oct 2008
Posts: 268

Kudos [?]: 557 [0], given: 22

Re: Exponents [#permalink]

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New post 17 Nov 2008, 02:28
Agreed.

Thanks for your suggestion. have edited the qs accordingly

Last edited by study on 17 Nov 2008, 04:13, edited 1 time in total.

Kudos [?]: 557 [0], given: 22

Director
Director
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Joined: 14 Aug 2007
Posts: 726

Kudos [?]: 222 [0], given: 0

Re: Exponents [#permalink]

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New post 17 Nov 2008, 02:37
study wrote:
I post questions exactly the way they are presented. I prefer not to alter the original qs, which could possibly alter its interpretation.

I am not asking you to alter original Q.
What I wanted to say is that, when you see, say 2^(3+x) on gmat
it is clear to you that it is \(2^(3+x)\), but when you post on forum it may look like (2^3)+ x. If you avoid such a confusion it wont make the question ambiguous.

Kudos [?]: 222 [0], given: 0

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Current Student
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Joined: 28 Dec 2004
Posts: 3345

Kudos [?]: 325 [1], given: 2

Location: New York City
Schools: Wharton'11 HBS'12
Re: Exponents [#permalink]

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New post 17 Nov 2008, 09:17
1
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KUDOS
you neeed to factor the power so that you can manipulate easily..

say you have 5^x and 5^x-1 then if you factor (5^x-1) *5^1=5^x

Kudos [?]: 325 [1], given: 2

Senior Manager
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Kudos [?]: 557 [0], given: 22

Re: Exponents [#permalink]

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New post 17 Nov 2008, 10:17
Thanks fresinha...

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Intern
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Joined: 19 Jun 2008
Posts: 20

Kudos [?]: 22 [0], given: 0

Re: Exponents [#permalink]

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New post 17 Nov 2008, 12:49
fresinha12 wrote:
study wrote:
How do you solve for this?

5^k - 5 ^k-1

Do not have the AC - only have the OA, will post it later.



5^(k-1)(5-1) =4*5^(k-1)



I don't understand where the (5-1) comes from...


I get it.. after 40 mins.. Jeez

Kudos [?]: 22 [0], given: 0

Re: Exponents   [#permalink] 17 Nov 2008, 12:49
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