- #1
alphamu
- 2
- 0
Question: Let n be a positive integer and consider x,y,z to be elements of Zn. Prove that if x . y = 1 and x . z = 1, then y = z. (Since working in Zn the sign '.' means "multiplication modulo n".)
Conclude that if x has an inverse element in Zn, then the inverse element is unique.
Attempt: Well if x . y = 1 then this means that xy = n + 1 since were working in Zn. This means the same can be said about y . z = 1 that yz = n + 1. This suggests that z = x by substitution. I'm not sure of this is correct or if I'm going down right path here.
Other thing I thought about was multiplying x . y = 1 by z on both sides to prove y=z but I'm a bit stuck.
I'm also a bit confused about the last bit of the question where I have to conclude if x has inverse element (not entirely sure what this is) in Zn then the inverse element is unique.
Can anyone help please?Sent from my iPhone using Physics Forums
Conclude that if x has an inverse element in Zn, then the inverse element is unique.
Attempt: Well if x . y = 1 then this means that xy = n + 1 since were working in Zn. This means the same can be said about y . z = 1 that yz = n + 1. This suggests that z = x by substitution. I'm not sure of this is correct or if I'm going down right path here.
Other thing I thought about was multiplying x . y = 1 by z on both sides to prove y=z but I'm a bit stuck.
I'm also a bit confused about the last bit of the question where I have to conclude if x has inverse element (not entirely sure what this is) in Zn then the inverse element is unique.
Can anyone help please?Sent from my iPhone using Physics Forums