Find the points where the function is not differentiable


by zorro
Tags: differentiable, function, points
zorro
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#1
Dec1-10, 05:52 AM
P: 1,395
1. The problem statement, all variables and given/known data
Find the points where the function given by

is not differentiable.

3. The attempt at a solution

I got the doubtful points as +-1, 2
How do I check the differentiability now? The mod. function is confusing me a bit.
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micromass
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#2
Dec1-10, 07:20 AM
Mentor
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P: 16,692
You should transform this function in a piecewize function.

That is, the doubtfull points are those when x2-3x+2=0 and x=0.
Once you've determined these points, you can write your function is piecewise form...
zorro
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#3
Dec1-10, 11:32 AM
P: 1,395
My book says 1,-1,2 are the possible points of non-differentiability.
Can you tell me how -1 is included?
Moreover, 0 as you told would not be a doubt full point as cos(modx) is same as cosx

micromass
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#4
Dec1-10, 11:39 AM
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P: 16,692

Find the points where the function is not differentiable


-1 is not a point of non-differentiability, at least not if you follow my method. Maybe the book uses other methods.

You are correct about 0. Thus 1 and 2 are the only possible points of non-differentiability...


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