- #1
zoner7
- 90
- 0
Homework Statement
Let n>1 be an integer, and let a be a fixed integer, prove or disprove that the set
E will stand for is an element of
H = {xEZ| ax = (mod n) is a subgroup under addition.
The Attempt at a Solution
I recognized that ax = a + a + a... + a. I figured this might help me along the way,s ince I am trying to prove ax a subgroup under addition.
Assume H is a subgroup under addition.
(From here I hope to prove that H fulfills all of the prerequisites of a subgroup (1. non-empty 2. is closed 3. every number has an inverse). If it does not, by contradiction I can prove that H is not a subgroup under addition.)
1. Since a is a fixed integer and is contained contained in the set H, we know that H is non-empty.
I'm not too sure what to do from here.
2. Since ax = 0(mod n), ax = nq for some q.
Do we need to prove that a and x are in H at all, since the set cannot be closed if they aren't... it only says ax is contained in H.
then we would need to show that a + a + a ... + a = 0(mod n) is contained in H.
Could we possibly use inductions to solve this?
thanks for the help in advance