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Hi all

I have f(x)=|x|. This I write as

f(x) = -x for x<0

f(x) = x for x>0

f(x) = 0 for x=0

If I want to show that f(x) is not differentiable at x=0, then is it enough to show that

f'(x) = -1 for x<0

f'(x) = 1 for x>0

and from this conclude that it is not differentiable at x=0? I am a little worried about f(x) at x=0.

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# Homework Help: Absolute value and differentiability

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