gmat prep question

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 144
Joined: Wed Feb 07, 2007 4:13 pm

gmat prep question

by yvonne12 » Sun Apr 15, 2007 6:00 pm
if z^n=1 whaty is the value of z

1. n is a non zero integer

2. z>0

I thought it was A since, z^n=1 and n is non zero z must be 1 becuase n could've been 0.

why is it both??

User avatar
Community Manager
Posts: 789
Joined: Sun Jan 28, 2007 3:51 pm
Location: Silicon valley, California
Thanked: 30 times
Followed by:1 members

Re: gmat prep question

by jayhawk2001 » Sun Apr 15, 2007 9:00 pm
yvonne12 wrote:if z^n=1 whaty is the value of z

1. n is a non zero integer

2. z>0

I thought it was A since, z^n=1 and n is non zero z must be 1 becuase n could've been 0.

why is it both??
1 tells us that z can be +1 or -1. Based on whether n is even or odd,
we can get z^n = 1. Hence insufficient.

2 tells us that z > 0 which is insufficient by itself. If n is zero, z^n =1 for
any value of z > 0

Taking 1 and 2, we get z = +1.

Hence C

Master | Next Rank: 500 Posts
Posts: 144
Joined: Wed Feb 07, 2007 4:13 pm

yes

by yvonne12 » Mon Apr 16, 2007 4:30 pm
yes, of course, I forgot about the sign difference. Geez thats something that I should automatically know by now.... 13 more days to go...