Give proof and make two questions related to the Theorem

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
Section: Chapter Questions
Problem 1RQ
icon
Related questions
Topic Video
Question
Give proof and make two questions related to the Theorem
There are various methods for determining whether certain special types of
Mersenne numbers are prime or composite. One such test is presented next.
NUMBERS OF SPECIAL FORM
229
Theorem 11.3. If p and q = 2p+1 are primes, then either q |Mp or q| Mp+ 2, but
not both.
Proof. With reference to Fermat's theorem, we know that
29-1-1=0 (mod q)
and, factoring the left-hand side, that
(24-1)/2 - 1)(2q-)/2 + 1) = (2P - 1)(2P + 1)
=0 (mod q)
What amounts to the same thing:
Mp(M, +2) = 0 (mod q)
The stated conclusion now follows directly from Theorem 3.1. We cannot have both
9q |Mp and q | Mp +2, for then q | 2, which is impossible.
A single application should suffice to illustrate Theorem 11.3: if p = 23, then
9 = 2p + 1 = 47 is also a prime, so that we may consider the case of M23. The
question reduces to one of whether 47 | M23 or, to put it differently, whether 223 =
1 (mod 47). Now, we have
223 = 2°(2°)ª = 2°(-15)*(mod 47)
But
(-15)* = (225) = (-10)°
= 6 (mod 47)
Putting these two congruences together, we see that
223 = 23.6 = 48 = 1 (mod 47)
whence M23 is composite.
We might point out that Theorem 11.3 is of no help in testing the primality of
M29, say; in this instance, 59{ M29, but instead 59| M29 + 2.
Of the two possibilities q| M, or q| Mp+ 2, is it reasonable to ask: What
conditions on q will ensure that a LM.? The answer is to be found in Theorem 11.4.
Theorem 11.4. If g = 2n +l is prime, then we have the following:
7 (mod 8)
Transcribed Image Text:There are various methods for determining whether certain special types of Mersenne numbers are prime or composite. One such test is presented next. NUMBERS OF SPECIAL FORM 229 Theorem 11.3. If p and q = 2p+1 are primes, then either q |Mp or q| Mp+ 2, but not both. Proof. With reference to Fermat's theorem, we know that 29-1-1=0 (mod q) and, factoring the left-hand side, that (24-1)/2 - 1)(2q-)/2 + 1) = (2P - 1)(2P + 1) =0 (mod q) What amounts to the same thing: Mp(M, +2) = 0 (mod q) The stated conclusion now follows directly from Theorem 3.1. We cannot have both 9q |Mp and q | Mp +2, for then q | 2, which is impossible. A single application should suffice to illustrate Theorem 11.3: if p = 23, then 9 = 2p + 1 = 47 is also a prime, so that we may consider the case of M23. The question reduces to one of whether 47 | M23 or, to put it differently, whether 223 = 1 (mod 47). Now, we have 223 = 2°(2°)ª = 2°(-15)*(mod 47) But (-15)* = (225) = (-10)° = 6 (mod 47) Putting these two congruences together, we see that 223 = 23.6 = 48 = 1 (mod 47) whence M23 is composite. We might point out that Theorem 11.3 is of no help in testing the primality of M29, say; in this instance, 59{ M29, but instead 59| M29 + 2. Of the two possibilities q| M, or q| Mp+ 2, is it reasonable to ask: What conditions on q will ensure that a LM.? The answer is to be found in Theorem 11.4. Theorem 11.4. If g = 2n +l is prime, then we have the following: 7 (mod 8)
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 3 steps

Blurred answer
Knowledge Booster
Propositional Calculus
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, advanced-math and related others by exploring similar questions and additional content below.
Recommended textbooks for you
Advanced Engineering Mathematics
Advanced Engineering Mathematics
Advanced Math
ISBN:
9780470458365
Author:
Erwin Kreyszig
Publisher:
Wiley, John & Sons, Incorporated
Numerical Methods for Engineers
Numerical Methods for Engineers
Advanced Math
ISBN:
9780073397924
Author:
Steven C. Chapra Dr., Raymond P. Canale
Publisher:
McGraw-Hill Education
Introductory Mathematics for Engineering Applicat…
Introductory Mathematics for Engineering Applicat…
Advanced Math
ISBN:
9781118141809
Author:
Nathan Klingbeil
Publisher:
WILEY
Mathematics For Machine Technology
Mathematics For Machine Technology
Advanced Math
ISBN:
9781337798310
Author:
Peterson, John.
Publisher:
Cengage Learning,
Basic Technical Mathematics
Basic Technical Mathematics
Advanced Math
ISBN:
9780134437705
Author:
Washington
Publisher:
PEARSON
Topology
Topology
Advanced Math
ISBN:
9780134689517
Author:
Munkres, James R.
Publisher:
Pearson,