GRE Prep Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Fermat primes are prime numbers that can be written in the f
[#permalink]
22 Apr 2020, 12:37
22 Apr 2020, 12:37
Expert Reply
00:00
Question Stats:
90% (00:52) correct
10% (01:01) wrong based on 10 sessions
Hide Show timer Statistics
Fermat primes are prime numbers that can be written in the form \(2^k+1\), where k is an integer and a power of 2. Which of the following is NOT a Fermat prime
A. 3
B. 5
C. 17
D. 31
E. 257
A. 3
B. 5
C. 17
D. 31
E. 257
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: Fermat primes are prime numbers that can be written in the f
[#permalink]
22 Apr 2020, 12:57
22 Apr 2020, 12:57
1
Carcass wrote:
Fermat primes are prime numbers that can be written in the form \(2^k+1\), where k is an integer and a power of 2. Which of the following is NOT a Fermat prime
A. 3
B. 5
C. 17
D. 31
E. 257
A. 3
B. 5
C. 17
D. 31
E. 257
GIVEN: k is an integer and a power of 2
Some powers of 2 are: 1 (since 2⁰ = 1), 2 (since 2¹ = 2) , 4, 8, 16, .... etc
So, the Fermat primes are as follows:
2^k + 1 = 2^1 + 1 = 2 + 1 = 3 (eliminate A)
2^k + 1 = 2^2 + 1 = 4 + 1 = 5 (eliminate B)
2^k + 1 = 2^4 + 1 = 16 + 1 = 17 (eliminate C)
2^k + 1 = 2^8 + 1 = 256 + 1 = 257 (eliminate E)
By the process of elimination (POE), the correct answer is D
Cheers,
Brent
gmatclubot
Re: Fermat primes are prime numbers that can be written in the f [#permalink]
22 Apr 2020, 12:57
Moderators:
