A function is differentiable at a point if its derivative exists there — meaning the curve is smooth, no corner or break.
Differentiable ⇒ continuous, but continuous doesn't imply differentiable. |x| is continuous at 0 but has a corner.
A function is differentiable at a point if its derivative exists there — meaning the curve is smooth, no corner or break.
Differentiable ⇒ continuous, but continuous doesn't imply differentiable. |x| is continuous at 0 but has a corner.