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# 5^(x-1)/5^(-1-2x) is equal to which of the following?

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Math Revolution GMAT Instructor
Joined: 16 Aug 2015
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5^(x-1)/5^(-1-2x) is equal to which of the following?  [#permalink]

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Updated on: 20 Oct 2016, 07:27
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Difficulty:

15% (low)

Question Stats:

79% (01:15) correct 21% (01:49) wrong based on 110 sessions

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$$\frac{5^{x-1}}{5^{-1-2x}}$$ is equal to which of the following?

A. 5^(x-1)
B. 5^(1-x)
C. 25^2x
D. 25^-2x
E. 125^x

* A solution will be posted in 2 days.

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MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
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"Only $79 for 1 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Originally posted by MathRevolution on 19 Oct 2016, 23:43. Last edited by Abhishek009 on 20 Oct 2016, 07:27, edited 1 time in total. Edited for better representation Board of Directors Status: Stepping into my 10 years long dream Joined: 18 Jul 2015 Posts: 3582 5^(x-1)/5^(-1-2x) is equal to which of the following? [#permalink] ### Show Tags 20 Oct 2016, 06:18 MathRevolution wrote: 5^(x-1)/5^(-1-2x) is equal to which of the following? A. 5^(x-1) B. 5^(1-x) C. 25^2x D. 25^-2x E. 125^x * A solution will be posted in 2 days. $$5^(x-1)/5^(-1-2x)$$ = $$5^(x-1) * 5^(1+2x)$$ = $$5^(3x)$$ = $$125^x$$ Hence, E _________________ My LinkedIn abhimahna. My GMAT Story: From V21 to V40 My MBA Journey: My 10 years long MBA Dream My Secret Hacks: Best way to use GMATClub | Importance of an Error Log! Verbal Resources: All SC Resources at one place | All CR Resources at one place GMAT Club Inbuilt Error Log Functionality - View More. New Visa Forum - Ask all your Visa Related Questions - here. New! Best Reply Functionality on GMAT Club! Find a bug in the new email templates and get rewarded with 2 weeks of GMATClub Tests for free Check our new About Us Page here. Board of Directors Status: QA & VA Forum Moderator Joined: 11 Jun 2011 Posts: 4778 Location: India GPA: 3.5 WE: Business Development (Commercial Banking) Re: 5^(x-1)/5^(-1-2x) is equal to which of the following? [#permalink] ### Show Tags 20 Oct 2016, 07:30 MathRevolution wrote: $$\frac{5^{x-1}}{5^{-1-2x}}$$ is equal to which of the following? A. 5^(x-1) B. 5^(1-x) C. 25^2x D. 25^-2x E. 125^x * A solution will be posted in 2 days. $$\frac{5^{x-1}}{5^{-1-2x}}$$ = $$5^{(x-1) - ( -1-2x ) }$$ = $$5^{x-1 +1 + 2x ) }$$ = $$5^{3x}$$ = $$125^x$$ Answer will be (E) _________________ Thanks and Regards Abhishek.... PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS How to use Search Function in GMAT Club | Rules for Posting in QA forum | Writing Mathematical Formulas |Rules for Posting in VA forum | Request Expert's Reply ( VA Forum Only ) Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 8007 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: 5^(x-1)/5^(-1-2x) is equal to which of the following? [#permalink] ### Show Tags 24 Oct 2016, 01:16 ==>5^(x-1)/5^(-1-2x)=5^{x-1-(-1-2x)} = 5^(x-1+1+2x)=5^3x=(5^3)x=125^x. E is the answer. _________________ MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. "Only$79 for 1 month Online Course"
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Re: 5^(x-1)/5^(-1-2x) is equal to which of the following?  [#permalink]

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25 Oct 2016, 20:10
I got the answer right but could someone explain why 25^2x isn't the right answer?

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Math Revolution GMAT Instructor
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Re: 5^(x-1)/5^(-1-2x) is equal to which of the following?  [#permalink]

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26 Oct 2016, 22:00
gillyelephant wrote:
I got the answer right but could someone explain why 25^2x isn't the right answer?

Posted from my mobile device

Hi gillyelephant,

==> 5x-1/5-1-2x =5x-1-(-1-2x) = 5x-1+1+2x=53x=(53)x=125x
no 25^2x=(25^2)^x=625^x.

Hope it helps.
Thank you.
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Re: 5^(x-1)/5^(-1-2x) is equal to which of the following?  [#permalink]

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21 Mar 2018, 02:48
MathRevolution wrote:
$$\frac{5^{x-1}}{5^{-1-2x}}$$ is equal to which of the following?

A. 5^(x-1)
B. 5^(1-x)
C. 25^2x
D. 25^-2x
E. 125^x

* A solution will be posted in 2 days.

$$\frac{5^{x-1}}{5^{-1-2x}}$$

$$\frac{5^x * 5^-1}{5^-1* 5^{-2x}}$$

It can be written as,

$$5^x * 5^{2x}$$

$$5^{3x}$$

$$125^x$$

(E)
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Re: 5^(x-1)/5^(-1-2x) is equal to which of the following?   [#permalink] 21 Mar 2018, 02:48
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# 5^(x-1)/5^(-1-2x) is equal to which of the following?

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