how can i find the value of differentiation? that is f'(2)?

f=@(x) x^2- 4

a=diff(f,x)

a(2)? .... (i am getting error here)

Answer 1

[Alex Mcaulley]

syms x
f=x^2- 4

f = 

a(x)=diff(f,x)

a(x) = 

a(2)

ans = 

4