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#3
Sep10-07, 08:02 PM
P: 17
This picture show what differential is for a function f(x)
http://www.bymath.com/studyguide/ana/sec/ana4a.gif
Basically, it is the change in the linear approximation for a function for a change in x, dx.

dy/dx = f '(x) -> differential dy = f '(x) dx
When dx is small dy is a good approximation for f(x + dx) - f(x);