# Compute derivative of a composed function leaving indicated some derivatives [closed]

Is there a way to define in Mathematica a generic differentiable function $g:\mathbb{R}^2\rightarrow \mathbb{R}$ in such a way that when it computes the derivatives of a composed function involving $g$ it leaves indicated the derivatives of $g$ instead of actually computing them?

I'll explain myself better with an example:

Suppose we have defined this "generic" $g:\mathbb{R}^2\rightarrow \mathbb{R}$ and we have defined $F:\mathbb{R}\rightarrow \mathbb{R}$, $F(x)=7Log[x]$. When given the command $D(F(g(x,y)),x)$ I would like to have the output $7\partial_x(g)/g$. Is it possible?

## closed as off-topic by march, Feyre, m_goldberg, Michael E2, happy fishOct 26 '16 at 6:32

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question arises due to a simple mistake such as a trivial syntax error, incorrect capitalization, spelling mistake, or other typographical error and is unlikely to help any future visitors, or else it is easily found in the documentation." – march, Feyre, m_goldberg, Michael E2, happy fish
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It is not only possible, it is actually quite straightforward. Define f in the usual way:
f[x_] := 7 Log[x]

Then take the derivative of the composition with g[x,y] (being an "undefined" generic function). The answer is as you expect:
D[f[g[x, y]], x]