## Calculus (3rd Edition)

$f(x)$ appears to be not differentiable at $x=3$ (the tangent line is vertical).
Given $$f(x)=(x-3)^{1 / 3}, \quad a=3$$ From the following figure, at $x=3, \ \ f(x)$ appears to be not differentiable (the tangent line is vertical there).