i need to show that there is x1 f(x1)<c
from the limit when x goes to sero we get zero soby limit definition -e<f(x)<e
from the limit when x goes minus infinity f(x)<-N
what e to chhose?
what N to choose?
Now, this interpretation is arguable and possibly not every everybody would agree that "only one" means <= 1 and "one" means ">= 1." I would therefore avoid statements containing "only one." However, since it is given, the default interpretation of this problem for me is to prove that there cannot be two solutions.
So, what exactly do you need to prove here? You may need to contact your instructor for clarification.