Understanding Modules: Definition and Properties for Homework

EV33
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Homework Statement


I am curious if all modules contain 0.

Homework Equations



A left R-module M over the ring R consists of an abelian group (M, +) and an operation R × M → M such that certain properties hold...

The Attempt at a Solution


The definition of a module says that it is an additive group, and additive groups have the zero element. Thus, all modules contain the zero element right?



Thank you.
 
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EV33 said:

Homework Statement


I am curious if all modules contain 0.

Homework Equations



A left R-module M over the ring R consists of an abelian group (M, +) and an operation R × M → M such that certain properties hold...

The Attempt at a Solution


The definition of a module says that it is an additive group, and additive groups have the zero element. Thus, all modules contain the zero element right?
Thank you.

If 'zero' means the additive identity of the group, sure.
 
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Note that the ring, R, also has a "0" (additive identity) which is not necessarily the additive identity of M.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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