# Re: i need help pronto por favor!

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Posted by Brad Paul on October 08, 2002 at 19:17:32:

In Reply to: i need help pronto por favor! posted by shawn on October 08, 2002 at 18:37:53:

: ok. i have the points (-4,0) (0,2) (1,-2) (4,-2) (6,2) all plotted on a plane and connected together. i am supposed to graph the derivative of y=f(x) and tell at what values the funtion isn't differentiable. i dont know how to find the derivative of such a crazy graph. i was thinking the points where it isn't differentiable would be the points i listed at the beginning b/c they are corners. right? help quickly please. thanks.

Technically there is not enough information to answer your
question. There are an infinite number of functions that can go
through the points you have given. I need to know more about the
function that connects the points.

However I would guess the full question connects the points with
straight lines. In that case you are correct, that at the points, if
the slope is discontinuous, the function is not differentiable. Find
the slope between each consecutive pair of points. If the slope is
different between two regions then the point in the middle can not have
a well defined derivative.

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