f(x) = x^3 - 2x, x<=2

Question

x + 2, x>2

Why do they say f'(2) is undefined?
TIA

I a f' = 3x^2-2 x<=2 and f'(2)=10

f' = 1 x>2 f'(2+)= 1

So although f(x) is continous at x=2, the curve f' is not. Therefore, f'(2) is undefined. Remember the basic definition of f' in limits, from the left, and right.