For

I want to know where is differentiable/not differentiable. I know it is differentiable at .. but I kind of cheated and used the Squeeze Theorem to prove that.

I now want to that to show that isnotdifferentiable at the only other point where it is continuous, i.e. at . I don't know how to show it explicitly in limit form, however.

Any help or tips are appreciated - thanks in advance!