For the function f:R -->R which is
f(x): -1 when x<0
1 when x>0
0 when x=0
prove that there is no limit at x=0. I'm told I can use a proof by contradiction.
What do you guys think? I've seen I can do something with derivatives or something, but I haven't been taught that yet. I just learned delta-epsilon proofs. (I looked at the sticky, but it wasn't helpful to me).
Thanks!
Regards,
Esther