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The function $f(x) = |x|$ is continuous everywhere but is NOT differentiable at:

A$x = -1$
B$x = 0$
Cevery point
D$x = 1$
Answer & 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).
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