Let f:R→Rf:\mathbb{R}\to\mathbb{R}f:R→R be the function f(x)=∣x∣+x2 ∀x∈Rf(x)=|x|+x^{2}\ \forall x\in\mathbb{R}f(x)=∣x∣+x2 ∀x∈R. Which of the following statements about fff is correct?
fff is differentiable
fff is concave but not differentiable
fff is convex but not differentiable
fff is discontinuous
