If 4^k = m

This topic has expert replies

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

If 4^k = m

by Brent@GMATPrepNow » Thu Jan 22, 2009 8:49 am
If 4^k = m, then 16^(4k+1) =
A) 4m^16
B) 8m^16
C) 16m^4
D) 16m^8
E) 256m^4

Please note that this is not an official GMAT question; it’s my attempt to create difficult (650+ level) GMAT-style questions for this forum.
Brent Hanneson - Creator of GMATPrepNow.com
Image
Source: — Problem Solving |

Master | Next Rank: 500 Posts
Posts: 139
Joined: Wed Oct 22, 2008 4:36 am
Thanked: 17 times

by sacx » Thu Jan 22, 2009 8:56 am
16^(4k+1) = 4^2(4k+1)
= 4^(8k+2)
= (4^8k)(4^2)
=[(4^k)^8] (4^2)
=[m^8](16) (from 4^k = m)
= 16(m^8)
SACX

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 16207
Joined: Mon Dec 08, 2008 6:26 pm
Location: Vancouver, BC
Thanked: 5254 times
Followed by:1268 members
GMAT Score:770

by Brent@GMATPrepNow » Thu Jan 22, 2009 9:07 am
Nice work - D it is
Brent Hanneson - Creator of GMATPrepNow.com
Image