How to have a implicit function of a symbolic variable in our expressions and calculations

Hello,

Lets say I have

syms x y z

and I want to have the following expression

A=(3*x+5*y+3*z+5)*(f(x)+z)

and I am looking to find

diff(A,x)

where f(x) is a function of x and I want to find the derivate of A with respect to x. Is there a way to write f(x) so that when differentiating A ,it shows it as ?

Appreciate any help.

Thanks a lot!

Answer 1

[Birdman]

Simply, you can define symbolic functions just like symbolic variables:

syms x y z f(x)
A=(3*x+5*y+3*z+5)*(f(x)+z);
diff(A,x)

ans = 

3*z + 3*f(x) + diff(f(x), x)*(3*x + 5*y + 3*z + 5)

[EllaD]

Awesome, Thanks! :)