In the beginning part of my book. There was a solution which says:
Given a set of negative integers, , where , we can build a set of positive numbers by a set builder notation such as
Since is only a dummy variable, I am wondering whether it's possible at all to built the set with ?
I am thinking: Since elements of are negative, where , and that , then ought to be positive, i.e. , so .
I contemplated about the question you asked--and of course, the poster immediately before you too helped me think. So, I wrote on a piece of paper
If and , then the elements of cannot be negative, despite being defined as
, it has to be nothing else but ,
so as gmatt said.
I am a little too slow, but I will have another 70 years (I meant 70 more years) to learn.
Thanks to both of you.
While I was switching things around, I confused myself and then asked question, but I have learned quite a bit though.
If there is any consolation, you do help me learn.