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

Redeem

tricky question

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |
Master | Next Rank: 500 Posts
Posts: 418
Joined: Wed Jun 11, 2008 5:29 am
Thanked: 65 times

by bluementor » Fri Mar 06, 2009 4:11 am
2^x – 2^(x-2)= 3(2^13)

Multiply both sides of the equation by 2^2:

2^(x+2) - 2^x = 3(2^15)

Factor out 2^x:

(2^x)(2^2 - 1) = 3(2^15)
(2^x)3 = 3(2^15)

Compare both sides and you will see that x = 15. Choose D.

-BM-
Last edited by bluementor on Fri Mar 06, 2009 10:13 am, edited 1 time in total.
Top
Senior | Next Rank: 100 Posts
Posts: 90
Joined: Mon Mar 02, 2009 6:06 am
Thanked: 3 times

by Baldini » Fri Mar 06, 2009 4:32 am
Thanks again bluementor.
Just a question - to go from step 1 to step 2 in your reasonining, would you have to multiply by 2^2?
GMAX
Top
Master | Next Rank: 500 Posts
Posts: 418
Joined: Wed Jun 11, 2008 5:29 am
Thanked: 65 times

by bluementor » Fri Mar 06, 2009 10:12 am
Baldini wrote:Thanks again bluementor.
Just a question - to go from step 1 to step 2 in your reasonining, would you have to multiply by 2^2?
ah yes...its multiplied by 2^2, not 2! Gosh, i'm making typos all over the place today...

Thanks,

-BM-
Top
Post new topic Post Reply
• Page 1 of 1