Question

difference between delta and differential

Answer 1

d and squiggly d?

Answer 2

\[\Delta z , dz\]

Answer 3

The former is any arbitrary size, the latter is infinitesimally small.

Answer 4

http://en.wikipedia.org/wiki/Inexact_differential

Answer 5

There are actually two graphs. One is the graph of the point, the other is the graph of the tangent line to that point. One is the change in the x, the other is the approximation.