How to write a code to calculate the f '(3)?

If f(x)=,then i want to know what is the value after i differential it and replace x with 3

I mean first i calculate f ' (x)=,then now i replace x with 3= f ' (3)== -5.4783

how do i write a code to calculate to the -5.4783?

I know i can use diff() to calculate the f ' (x),but how do i calculate the f ' (3) directly?

Answer 1

[darova]

Try symbolic expression

syms f(x)
f(x) = x^2;
f1 = diff(f);
f1(5)