Define:
f(x) = (x^2)sin(1/x)+x if x doesn't equal 0
f(x) = 0 if x=0
Prove that the function f:R-> R is differentiable and that f'(0)=1. Also prove that there is no neighbourhood I of 0 such that the function f:I->R is increasing.
This is a proof regarding differentiability of a function.