# Derivatives of Unknown Functions

Differentiating a known function gives an explicit result.
 In[1]:=
 Out[1]=
Differentiating an unknown function f gives a result in terms of f'.
 In[2]:=
 Out[2]=
The Wolfram Language applies the chain rule for differentiation, and leaves the result in terms of f'.
 In[3]:=
 Out[3]=
Differentiating again gives a result in terms of f, f', and f''.
 In[4]:=
 Out[4]=
When a function has more than one argument, superscripts are used to indicate how many times each argument is being differentiated.
 In[5]:=
 Out[5]=
This represents . The Wolfram Language assumes that the order in which derivatives are taken with respect to different variables is irrelevant.
 In[6]:=
 Out[6]=
You can find the value of the derivative when by replacing x with 0.
 In[7]:=
 Out[7]=
 f '[x] first derivative of a function of one variable f(n)[x] n derivative of a function of one variable Null derivative of a function of several variables, ni times with respect to variable i

Output forms for derivatives of unknown functions.