Hello, I have been looking around the net recently trying to teach myself how to do delta/epsilon proofs. unfortunately, my prof sucks . Anyway, I think I understand how to get delta in terms of epsilon for limits where x approaches a number, but I'm having difficulty finding what to do when x approaches a value 'a'. eg. prove: lim of x approaches a ( 1/x^3) = (1/a^3) I don't really need a solution, although it would be welcome. I'm just interested in what the usual procedure is for finding delta as I'm always stuck with an 'a' term and an 'x' term that I'm not sure what to do with or how to get rid of. Any help is greatly appreciated.