Register to reply

Rather basic question - I think

by Baggio
Tags: basic
Share this thread:
Nov4-04, 02:36 PM
P: 212
If a and N coprime, a < N and r is even how can

a^(r) = 1 mod(N) be written as

a^(r) - 1 = 0 mod(N) ?

I don't know much number theory (I'm a physics student)

Phys.Org News Partner Science news on
Flapping baby birds give clues to origin of flight
Prions can trigger 'stuck' wine fermentations, researchers find
Socially-assistive robots help kids with autism learn by providing personalized prompts
Nov4-04, 02:45 PM
Sci Advisor
HW Helper
P: 1,994
Hi, the conditions you list at the start don't matter for what you've just asked (a, N coprime, etc). For any a,b, and N,

a=b mod (N)

if and only if

N divides a-b

if and only if

N divides (a-b)-0

if and only if

a-b=0 mod(N)

Working mod N you can add, subtract and multiply as normal (division isn't always possible!), you just have the luxury of reducing things mod(N) afterwards.
Nov4-04, 03:54 PM
P: 212
ahh i see what you did there.. thanks!

Register to reply

Related Discussions
Basic question on F=ma Introductory Physics Homework 2
Basic question... General Engineering 4
Basic Log Question General Math 2
A Basic Set Question Precalculus Mathematics Homework 3
Very basic question F=ma Classical Physics 2