Which function f(x)f(x)f(x) is continuous on R\mathbb{R}R but NOT differentiable at x=0x=0x=0?
f(x)=x1/3f(x) = x^{1/3}f(x)=x1/3
f(x)=∣x∣xf(x) = |x| xf(x)=∣x∣x
f(x)=x2sin(1/x)f(x) = x^2 \sin(1/x)f(x)=x2sin(1/x)
f(x)=sin∣x∣f(x) = \sin|x|f(x)=sin∣x∣