[Blindmath] D Y verses Delta Y

[Suzanne Germano]

A google search came up with this answer for delta x and delta y vs dx and
dy

Δy/Δx denotes average rate of change in y over the interval of length Δx,
while dy/dx stands for the instantaneous rate of change as Δx approaches
zero.

The dy/dx notation is similar to that used by Leibniz, one of the founders
of Calculus.




On Thu, Apr 4, 2013 at 9:13 PM, GianniP46 <giannip46 at earthlink.net> wrote:

> Hi all,
> I am brushing up on some Calculus.  I find myself confused between the
> difference d y and delta y and d x and delta x.  It seams that d x and
> delta x are usually the same, but there is a difference between d y and
> delta y.
> For example, if you have a function Y = X squared, and you want to find d
> y and delta y at x = 2 and d x =1,
> Then
> D Y = 2X DX which = 2 times2 times 1 which =4
> Delta y = f of x plus delta x minus f of x
> which = (x + delta x) squared minus x squared
> which = (2+1) squared minus 2 squared
> which = 9  minus 4 = 5
> so d x = 4 and d y = 5.
>
> I understand that d y is the y component or the rise of the slope of the
> tangent line at x = 2 of x squared, but what does a delta y value of 5 mean
> for this function?
>
> The book I am looking at makes it seam that d y has to do with the y
> component of the tangent line and delta y has to do with the y component of
> the curve.  This is not making sense to me for some reason.  Can someone
> explain?  Feeling very dumb and frustrated right now. lol
>
>
> Gian Carlo Pedulla
> GianniP46 at earthlink.net
>
> LETS! GO! METS!
> _______________________________________________
> Blindmath mailing list
> Blindmath at nfbnet.org
> http://nfbnet.org/mailman/listinfo/blindmath_nfbnet.org
> To unsubscribe, change your list options or get your account info for
> Blindmath:
> http://nfbnet.org/mailman/options/blindmath_nfbnet.org/sgermano%40asu.edu
>