MHB Is this function differentiable at c=1?

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f'(x) is equal to the limit of x approaches to c of the (f(x)-f(c))/(x-c), and c=1.

f(x)=\begin{array}{cc}x,&\mbox{ if }
x\leq 1\\x^2, & \mbox{ if } x>1\end{array}The function is a piece wise function.Thanks

CBarker1
 
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You need to investigate two one-sided limits. Can you state these two limits?
 
Cbarker1 said:
f'(x) is equal to the limit of x approaches to c of the (f(x)-f(c))/(x-c), and c=1.

f(x)=\begin{array}{cc}x,&\mbox{ if }
x\leq 1\\x^2, & \mbox{ if } x>1\end{array}The function is a piece wise function.Thanks

CBarker1

The function is not differentiable at 1 because the limit from the left is 1 but the limit from the right is 2.
 
Fermat said:
The function is not differentiable at 1 because the limit from the left is 1 but the limit from the right is 2.

(Wait) I was actually hoping the OP could state the two one-sided limits and then discover these values on their own. (Nod)
 
I have worked out the problem. I see the limits are not equal to each other. Thank you.
 
For future reference:

A function is continuous at a point if the function is defined at that point, and also the left hand and right hand limits are both equal to that function value.

A function is differentiable at a point if the function is continuous at that point, and also if the derivative is continuous at that point.
 

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