Proving that $M\otimes N \approx N\otimes M$ (help needed) [duplicate]
This question is from my assignment in Tensor products and I need help in solving the problem. I have been following atiyah and macdonald.
Question : Prove that $M\otimes N\approx N\otimes M$.( Here M and N are modules)
I am not very good in Tensor products and here is what I thought:
Intuition is clear to me as if $C =A^{M\times N}$ and D is the submodule by Which I will factor C to get $M\otimes N$, then C is generated by elements which are additive and satisfy scalar multiplication wrt to both M and N. So, divison modulo it make $M\otimes N$ isomorphic to $N\otimes M$.
But for proving rigoriously , I need to find a map f which will map $M\otimes N \to N\otimes M$. This map will be from $A^{M\times N}/D \to A^{N\times M}/D$.
Can you please help me with the construction of such map?
I would try rest of proof by myself.
Thanks!
Hint: Use the universal property of the tensor product to construct linear maps $$M \otimes N \to N \otimes M: m \otimes n \mapsto n \otimes m$$ and $$N\otimes M \to M\otimes N: n \otimes m \mapsto m\otimes n.$$ Then show that these maps are inverse to each other.