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
Live EA class + 6 months of EA OnDemand
  • Expert-led weekly online sessions
  • EA Masterclass access between classes
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.

130-point 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.

Help with Radical Simplification

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Newbie | Next Rank: 10 Posts
Posts: 4
Joined: Thu Dec 04, 2008 4:03 pm
by Steve90036 » Fri Jul 10, 2009 6:46 pm
Hello, I am working on OG12 #154 (DS). I a using the GMAT Hacks Guide to the official guide, and can not for the life me, figure out how is simplified this equation:

3^n+1 - 2^n+1 = 3^n(3^1)- 2n(2^1) = 2 (1.5(3^n)-2^n)

I understand the the X^z+y=X^z*X^y

What I DO NOT understand is how he broke out a 2 and 1.5. Can someone please help me understand this.

Thanks,

-Steve
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
User avatar
Master | Next Rank: 500 Posts
Posts: 472
Joined: Sun Mar 29, 2009 6:54 pm
Thanked: 56 times

by ssmiles08 » Fri Jul 10, 2009 7:10 pm
I don't know what exactly you did there as I don't have GMAT hacks

but the question is asking if at least b - a = 2*(3^n - 2^n)

1) tells you a = 2^(n+1) and b = 3^(n+1)

from here you can substitute and see if: 3^(n+1) - 2^(n+1) = 2*(3^n - 2^n)?

2*(3^n - 2^n) = 2*3^n - 2^(n+1) when expanded.

as you can see then, 2*3^n - 2^(n+1) is NOT equal to 3^(n+1) - 2^(n+1), and is definitely less than the value of 3^(n+1) - 2^(n+1).

since we know that they are NOT equal and 2*3^n - 2^(n+1) < 3^(n+1) - 2^(n+1) , we can determine that this statement is sufficient.

2) gives you n= 3. Insufficient b/c doesn't tell us anything about a and b.

(A)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1