Homework Help: Why is this true?

1. Jun 19, 2006

Tuneman

if

and

then:

du/dx=

I think it is because:

$$du/dx= \Delta(u(\xi,\eta))$$

Last edited: Jun 19, 2006
2. Jun 20, 2006

HallsofIvy

I would think it was because
$$\frac{\partial \xi}{\partial x}= 1$$
and
$$\frac{\partial \eta}{\partial x}= 1$$

Since u is a function of two variables,
$$\frac{du}{dx}$$
isn't equal to anything!