f(x)= x/1+e^(1/x), x doesn't equal 0
defines a continuous function on R. Is f(x) differentiable?
I have no idea where to even begin. My teacher didn't even teach us this in class before assigning it...
You can get the first part
by taking the limit.
If it ain't broke, fix it until it is.
A number by itself is useful, but it is far more useful to know how accurate or certain that number is.