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

Redeem

There is a sequence An such that An+1=2An-1 and A1=3, where

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members

There is a sequence An such that An+1=2An-1 and A1=3, where

by Max@Math Revolution » Sun Jun 05, 2016 5:05 am
There is a sequence A(n) such that A(n+1)=2A(n)-1 and A(1)=3, where n is a positive integer. What is the value of A(24)-A(23)?
A. 2^22+1
B. 2^23
C. 2^23+1
D. 2^24
E. 2^23+1

*An answer will be posted in 2 days.
Top
Source: — Problem Solving |
User avatar
Elite Legendary Member
Posts: 3991
Joined: Fri Jul 24, 2015 2:28 am
Location: Las Vegas, USA
Thanked: 19 times
Followed by:37 members

by Max@Math Revolution » Mon Jun 06, 2016 8:56 pm
From A(1)=3=2+1, A(2)=2A(1)-1=5=2^2+1,...A(n)=2^n+1, we can calculate A(24)-A(23)=(2^24+1)-(2^23-1)=2^24-2^23=(2-1)2^23=2^23. Hence, the correct answer is B.
 
Top
Post new topic Post Reply
• Page 1 of 1