what is the nth term of this sequence -1/3,1/5,-1/7,1/9,...
Looks like you cooked this one up yourself, didn't you? It is faulty and has neither common ratio or common difference !!. And because of that, you cannot find its nth term!!.
If we waned to stretch things.......based on the pattern, the nth term is given by :
1 / [ (2n+ 1)(-1)n ]
Great thanks :-)