BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

★★★★★5.0559 reviews
GMATLiveTeach 7 seats left
Chris Peckover
NEXT LIVE COHORT

Oct 13 to Jan 7, 2027

with Chris Peckover

Schedule
Tue, Thu · 8:00 to 10:00 PM ET
Included
40 live hours + 6 months of GMAT OnDemand
  • Live instruction and real-time questions
  • Class recordings and assigned practice
View class & enroll
Limited cohort · enrollment openTarget Test Prep
EALiveTeach 5 seats left
Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

Schedule
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll
Limited cohort · enrollment openTarget Test Prep
GMATOnDemand Start anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 559 reviewsTarget Test Prep

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

exponents-rules

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 62
Joined: Mon Aug 02, 2010 3:25 pm
Thanked: 3 times
by Taniuca » Mon Nov 15, 2010 4:38 pm
I saw the other day a problem but I was never able to get to the solution.
I need someone to tell me which exponent rule it was used. Answer x=14

3^x - 3^(x-1)= (3^13)^2 I used the trick where x= (x-1)+1

3^[(x-1)+1] - 3^(x-1) = (3^13)^2 I factored 3^(x-1) from the left side of the equation.

3^(x-1)* (3-1) =(3^13)^2

3^(x-1) *2 = (3^13)^2 I don't see how we can solve x following exponent rules anymore.

Someone help me please!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members
Location: New York, NY
Thanked: 13060 times
GMAT Score:790

by GMATGuruNY » Mon Nov 15, 2010 5:19 pm
Taniuca wrote:I saw the other day a problem but I was never able to get to the solution.
I need someone to tell me which exponent rule it was used. Answer x=14

3^x - 3^(x-1)= (3^13)^2 I used the trick where x= (x-1)+1

3^[(x-1)+1] - 3^(x-1) = (3^13)^2 I factored 3^(x-1) from the left side of the equation.

3^(x-1)* (3-1) =(3^13)^2

3^(x-1) *2 = (3^13)^2 I don't see how we can solve x following exponent rules anymore.

Someone help me please!
You might find it easier to plug in the answer choices, which represent the value of x:

x=14:
3^x - 3^(x-1)= (3^13)*2
3^14 - 3^(14-1) = (3^13)*2
3^14 - 3^13 = (3^13)*2
3^13(3 - 1) = (3^13)*2
3^13(2) = (3^13)*2. Success!

If x=14 hadn't worked, we would have been able to see whether the correct exponent needed to be bigger or smaller.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 1179
Joined: Sun Apr 11, 2010 9:07 pmFollowed by: 88 members
Location: Milpitas, CA
Thanked: 447 times

by Rahul@gurome » Mon Nov 15, 2010 9:12 pm
Taniuca wrote:I saw the other day a problem but I was never able to get to the solution.
I need someone to tell me which exponent rule it was used. Answer x=14

3^x - 3^(x-1)= (3^13)^2 I used the trick where x= (x-1)+1

3^[(x-1)+1] - 3^(x-1) = (3^13)^2 I factored 3^(x-1) from the left side of the equation.

3^(x-1)* (3-1) =(3^13)^2

3^(x-1) *2 = (3^13)^2 I don't see how we can solve x following exponent rules anymore.

Someone help me please!
3^x - 3^(x-1)= (3^13)^2 is not possible for any real x. Because the LHS is always a even number, whereas the RHS is a power of 3, thus an odd number.

May be the correct expression is, 3^x - 3^(x-1)= (3^13)*2

Then you can easily proceed further with your steps,
As, 3^x - 3^(x - 1)= (3^13)*2
=> 3^[(x - 1) + 1] - 3^(x - 1) = (3^13)*2
=> 3^(x - 1)*(3 - 1) =(3^13)*2
=> 3^(x - 1)*2 = (3^13)*2
=> 3^(x - 1) = (3^13)
=> (x - 1) = 13
=> x = 14
Rahul Lakhani
Quant Expert
Gurome, Inc.
https://www.GuroMe.com
On MBA sabbatical (at ISB) for 2011-12 - will stay active as time permits
1-800-566-4043 (USA)
+91-99201 32411 (India)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1