The function $f(x) = |x|$ is continuous everywhere but is NOT differentiable at:
- $x = -1$
- $x = 0$
- every point
- $x = 1$
Show answer and solution
Correct answer: B. $x = 0$
|x| has a corner at 0: left slope −1, right slope +1, so it is not differentiable there (though continuous).